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60bb39431a
Specifically, it is required for the I/O that may be performed by elfN_load_section(). Avoid an obscure deadlock in the a.out, elf, and gzip image activators. Add a comment describing why the deadlock does not occur in the common case and how it might occur in less usual circumstances. Eliminate an unused variable from exec_aout_imgact(). In collaboration with: tegge
400 lines
9.9 KiB
C
400 lines
9.9 KiB
C
/*-
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* ----------------------------------------------------------------------------
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* "THE BEER-WARE LICENSE" (Revision 42):
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* <phk@FreeBSD.org> wrote this file. As long as you retain this notice you
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* can do whatever you want with this stuff. If we meet some day, and you think
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* this stuff is worth it, you can buy me a beer in return. Poul-Henning Kamp
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* ----------------------------------------------------------------------------
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*/
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/*
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* This module handles execution of a.out files which have been run through
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* "gzip". This saves diskspace, but wastes cpu-cycles and VM.
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*
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* TODO:
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* text-segments should be made R/O after being filled
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* is the vm-stuff safe ?
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* should handle the entire header of gzip'ed stuff.
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* inflate isn't quite reentrant yet...
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* error-handling is a mess...
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* so is the rest...
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* tidy up unnecesary includes
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*/
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#include <sys/cdefs.h>
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__FBSDID("$FreeBSD$");
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#include <sys/param.h>
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#include <sys/exec.h>
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#include <sys/imgact.h>
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#include <sys/imgact_aout.h>
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#include <sys/kernel.h>
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#include <sys/lock.h>
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#include <sys/mman.h>
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#include <sys/mutex.h>
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#include <sys/proc.h>
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#include <sys/resourcevar.h>
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#include <sys/sysent.h>
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#include <sys/systm.h>
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#include <sys/vnode.h>
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#include <sys/inflate.h>
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#include <vm/vm.h>
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#include <vm/vm_param.h>
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#include <vm/pmap.h>
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#include <vm/vm_map.h>
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#include <vm/vm_kern.h>
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#include <vm/vm_extern.h>
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struct imgact_gzip {
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struct image_params *ip;
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struct exec a_out;
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int error;
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int gotheader;
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int where;
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u_char *inbuf;
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u_long offset;
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u_long output;
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u_long len;
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int idx;
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u_long virtual_offset, file_offset, file_end, bss_size;
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};
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static int exec_gzip_imgact(struct image_params *imgp);
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static int NextByte(void *vp);
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static int do_aout_hdr(struct imgact_gzip *);
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static int Flush(void *vp, u_char *, u_long siz);
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static int
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exec_gzip_imgact(imgp)
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struct image_params *imgp;
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{
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int error, error2 = 0;
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const u_char *p = (const u_char *) imgp->image_header;
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struct imgact_gzip igz;
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struct inflate infl;
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struct vmspace *vmspace;
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/* If these four are not OK, it isn't a gzip file */
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if (p[0] != 0x1f)
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return -1; /* 0 Simply magic */
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if (p[1] != 0x8b)
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return -1; /* 1 Simply magic */
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if (p[2] != 0x08)
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return -1; /* 2 Compression method */
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if (p[9] != 0x03)
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return -1; /* 9 OS compressed on */
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/*
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* If this one contains anything but a comment or a filename marker,
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* we don't want to chew on it
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*/
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if (p[3] & ~(0x18))
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return ENOEXEC; /* 3 Flags */
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/* These are of no use to us */
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/* 4-7 Timestamp */
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/* 8 Extra flags */
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bzero(&igz, sizeof igz);
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bzero(&infl, sizeof infl);
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infl.gz_private = (void *) &igz;
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infl.gz_input = NextByte;
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infl.gz_output = Flush;
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igz.ip = imgp;
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igz.idx = 10;
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if (p[3] & 0x08) { /* skip a filename */
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while (p[igz.idx++])
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if (igz.idx >= PAGE_SIZE)
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return ENOEXEC;
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}
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if (p[3] & 0x10) { /* skip a comment */
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while (p[igz.idx++])
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if (igz.idx >= PAGE_SIZE)
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return ENOEXEC;
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}
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igz.len = imgp->attr->va_size;
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error = inflate(&infl);
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/*
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* The unzipped file may not even have been long enough to contain
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* a header giving Flush() a chance to return error. Check for this.
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*/
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if ( !igz.gotheader )
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return ENOEXEC;
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if ( !error ) {
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vmspace = imgp->proc->p_vmspace;
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error = vm_map_protect(&vmspace->vm_map,
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(vm_offset_t) vmspace->vm_taddr,
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(vm_offset_t) (vmspace->vm_taddr +
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(vmspace->vm_tsize << PAGE_SHIFT)) ,
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VM_PROT_READ|VM_PROT_EXECUTE,0);
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}
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if (igz.inbuf) {
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error2 =
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vm_map_remove(kernel_map, (vm_offset_t) igz.inbuf,
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(vm_offset_t) igz.inbuf + PAGE_SIZE);
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}
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if (igz.error || error || error2) {
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printf("Output=%lu ", igz.output);
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printf("Inflate_error=%d igz.error=%d error2=%d where=%d\n",
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error, igz.error, error2, igz.where);
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}
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if (igz.error)
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return igz.error;
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if (error)
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return ENOEXEC;
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if (error2)
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return error2;
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return 0;
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}
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static int
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do_aout_hdr(struct imgact_gzip * gz)
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{
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int error;
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struct thread *td = curthread;
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struct vmspace *vmspace;
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vm_offset_t vmaddr;
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/*
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* Set file/virtual offset based on a.out variant. We do two cases:
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* host byte order and network byte order (for NetBSD compatibility)
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*/
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switch ((int) (gz->a_out.a_magic & 0xffff)) {
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case ZMAGIC:
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gz->virtual_offset = 0;
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if (gz->a_out.a_text) {
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gz->file_offset = PAGE_SIZE;
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} else {
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/* Bill's "screwball mode" */
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gz->file_offset = 0;
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}
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break;
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case QMAGIC:
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gz->virtual_offset = PAGE_SIZE;
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gz->file_offset = 0;
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break;
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default:
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/* NetBSD compatibility */
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switch ((int) (ntohl(gz->a_out.a_magic) & 0xffff)) {
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case ZMAGIC:
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case QMAGIC:
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gz->virtual_offset = PAGE_SIZE;
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gz->file_offset = 0;
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break;
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default:
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gz->where = __LINE__;
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return (-1);
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}
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}
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gz->bss_size = roundup(gz->a_out.a_bss, PAGE_SIZE);
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/*
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* Check various fields in header for validity/bounds.
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*/
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if ( /* entry point must lay with text region */
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gz->a_out.a_entry < gz->virtual_offset ||
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gz->a_out.a_entry >= gz->virtual_offset + gz->a_out.a_text ||
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/* text and data size must each be page rounded */
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gz->a_out.a_text & PAGE_MASK || gz->a_out.a_data & PAGE_MASK) {
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gz->where = __LINE__;
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return (-1);
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}
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/*
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* text/data/bss must not exceed limits
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*/
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PROC_LOCK(gz->ip->proc);
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if ( /* text can't exceed maximum text size */
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gz->a_out.a_text > maxtsiz ||
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/* data + bss can't exceed rlimit */
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gz->a_out.a_data + gz->bss_size >
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lim_cur(gz->ip->proc, RLIMIT_DATA)) {
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PROC_UNLOCK(gz->ip->proc);
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gz->where = __LINE__;
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return (ENOMEM);
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}
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PROC_UNLOCK(gz->ip->proc);
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/* Find out how far we should go */
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gz->file_end = gz->file_offset + gz->a_out.a_text + gz->a_out.a_data;
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/*
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* Avoid a possible deadlock if the current address space is destroyed
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* and that address space maps the locked vnode. In the common case,
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* the locked vnode's v_usecount is decremented but remains greater
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* than zero. Consequently, the vnode lock is not needed by vrele().
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* However, in cases where the vnode lock is external, such as nullfs,
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* v_usecount may become zero.
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*/
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VOP_UNLOCK(gz->ip->vp, 0, td);
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/*
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* Destroy old process VM and create a new one (with a new stack)
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*/
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exec_new_vmspace(gz->ip, &aout_sysvec);
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vn_lock(gz->ip->vp, LK_EXCLUSIVE | LK_RETRY, td);
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vmspace = gz->ip->proc->p_vmspace;
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vmaddr = gz->virtual_offset;
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error = vm_mmap(&vmspace->vm_map,
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&vmaddr,
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gz->a_out.a_text + gz->a_out.a_data,
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VM_PROT_ALL, VM_PROT_ALL, MAP_ANON | MAP_FIXED,
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OBJT_DEFAULT,
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NULL,
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0);
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if (error) {
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gz->where = __LINE__;
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return (error);
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}
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if (gz->bss_size != 0) {
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/*
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* Allocate demand-zeroed area for uninitialized data.
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* "bss" = 'block started by symbol' - named after the
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* IBM 7090 instruction of the same name.
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*/
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vmaddr = gz->virtual_offset + gz->a_out.a_text +
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gz->a_out.a_data;
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error = vm_map_find(&vmspace->vm_map,
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NULL,
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0,
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&vmaddr,
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gz->bss_size,
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FALSE, VM_PROT_ALL, VM_PROT_ALL, 0);
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if (error) {
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gz->where = __LINE__;
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return (error);
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}
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}
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/* Fill in process VM information */
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vmspace->vm_tsize = gz->a_out.a_text >> PAGE_SHIFT;
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vmspace->vm_dsize = (gz->a_out.a_data + gz->bss_size) >> PAGE_SHIFT;
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vmspace->vm_taddr = (caddr_t) (uintptr_t) gz->virtual_offset;
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vmspace->vm_daddr = (caddr_t) (uintptr_t)
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(gz->virtual_offset + gz->a_out.a_text);
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/* Fill in image_params */
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gz->ip->interpreted = 0;
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gz->ip->entry_addr = gz->a_out.a_entry;
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gz->ip->proc->p_sysent = &aout_sysvec;
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return 0;
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}
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static int
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NextByte(void *vp)
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{
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int error;
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struct imgact_gzip *igz = (struct imgact_gzip *) vp;
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if (igz->idx >= igz->len) {
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igz->where = __LINE__;
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return GZ_EOF;
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}
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if (igz->inbuf && igz->idx < (igz->offset + PAGE_SIZE)) {
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return igz->inbuf[(igz->idx++) - igz->offset];
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}
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if (igz->inbuf) {
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error = vm_map_remove(kernel_map, (vm_offset_t) igz->inbuf,
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(vm_offset_t) igz->inbuf + PAGE_SIZE);
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if (error) {
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igz->where = __LINE__;
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igz->error = error;
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return GZ_EOF;
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}
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}
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igz->offset = igz->idx & ~PAGE_MASK;
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error = vm_mmap(kernel_map, /* map */
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(vm_offset_t *) & igz->inbuf, /* address */
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PAGE_SIZE, /* size */
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VM_PROT_READ, /* protection */
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VM_PROT_READ, /* max protection */
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0, /* flags */
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OBJT_VNODE, /* handle type */
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igz->ip->vp, /* vnode */
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igz->offset); /* offset */
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if (error) {
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igz->where = __LINE__;
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igz->error = error;
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return GZ_EOF;
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}
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return igz->inbuf[(igz->idx++) - igz->offset];
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}
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static int
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Flush(void *vp, u_char * ptr, u_long siz)
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{
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struct imgact_gzip *gz = (struct imgact_gzip *) vp;
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u_char *p = ptr, *q;
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int i;
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/* First, find an a.out-header. */
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if (gz->output < sizeof gz->a_out) {
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q = (u_char *) & gz->a_out;
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i = min(siz, sizeof gz->a_out - gz->output);
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bcopy(p, q + gz->output, i);
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gz->output += i;
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p += i;
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siz -= i;
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if (gz->output == sizeof gz->a_out) {
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gz->gotheader = 1;
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i = do_aout_hdr(gz);
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if (i == -1) {
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if (!gz->where)
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gz->where = __LINE__;
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gz->error = ENOEXEC;
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return ENOEXEC;
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} else if (i) {
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gz->where = __LINE__;
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gz->error = i;
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return ENOEXEC;
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}
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if (gz->file_offset == 0) {
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q = (u_char *) (uintptr_t) gz->virtual_offset;
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copyout(&gz->a_out, q, sizeof gz->a_out);
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}
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}
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}
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/* Skip over zero-padded first PAGE if needed */
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if (gz->output < gz->file_offset &&
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gz->output + siz > gz->file_offset) {
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i = min(siz, gz->file_offset - gz->output);
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gz->output += i;
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p += i;
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siz -= i;
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}
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if (gz->output >= gz->file_offset && gz->output < gz->file_end) {
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i = min(siz, gz->file_end - gz->output);
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q = (u_char *) (uintptr_t)
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(gz->virtual_offset + gz->output - gz->file_offset);
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copyout(p, q, i);
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gz->output += i;
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p += i;
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siz -= i;
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}
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gz->output += siz;
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return 0;
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}
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/*
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* Tell kern_execve.c about it, with a little help from the linker.
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*/
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static struct execsw gzip_execsw = {exec_gzip_imgact, "gzip"};
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EXEC_SET(execgzip, gzip_execsw);
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