4f294c247f
This patch mainly copies and modifies files existing in the current libc implementing minix specific functions. To keep consisten with the NetBSD libc, we remove namespace stubs and we use "namespace.h" and weak links.
118 lines
2.6 KiB
C
118 lines
2.6 KiB
C
/* execve() - basic program execution call Author: Kees J. Bot
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* 21 Jan 1994
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*/
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#define _MINIX_SOURCE
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#include <sys/cdefs.h>
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#include "namespace.h"
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#include <lib.h>
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#include <unistd.h>
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#include <string.h>
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#include <stddef.h>
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#ifdef __weak_alias
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__weak_alias(execve, _execve)
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#endif
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int execve(const char *path, char * const *argv, char * const *envp)
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{
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char * const *ap;
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char * const *ep;
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char *frame;
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char **vp;
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char *sp;
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size_t argc;
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size_t frame_size;
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size_t string_off;
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size_t n;
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int ov;
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message m;
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/* Assumptions: size_t and char *, it's all the same thing. */
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/* Create a stack image that only needs to be patched up slightly
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* by the kernel to be used for the process to be executed.
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*/
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ov= 0; /* No overflow yet. */
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frame_size= 0; /* Size of the new initial stack. */
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string_off= 0; /* Offset to start of the strings. */
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argc= 0; /* Argument count. */
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for (ap= argv; *ap != NULL; ap++) {
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n = sizeof(*ap) + strlen(*ap) + 1;
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frame_size+= n;
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if (frame_size < n) ov= 1;
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string_off+= sizeof(*ap);
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argc++;
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}
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for (ep= envp; *ep != NULL; ep++) {
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n = sizeof(*ep) + strlen(*ep) + 1;
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frame_size+= n;
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if (frame_size < n) ov= 1;
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string_off+= sizeof(*ap);
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}
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/* Add an argument count and two terminating nulls. */
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frame_size+= sizeof(argc) + sizeof(*ap) + sizeof(*ep);
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string_off+= sizeof(argc) + sizeof(*ap) + sizeof(*ep);
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/* Align. */
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frame_size= (frame_size + sizeof(char *) - 1) & ~(sizeof(char *) - 1);
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/* The party is off if there is an overflow. */
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if (ov || frame_size < 3 * sizeof(char *)) {
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errno= E2BIG;
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return -1;
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}
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/* Allocate space for the stack frame. */
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if ((frame = (char *) sbrk(frame_size)) == (char *) -1) {
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errno = E2BIG;
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return -1;
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}
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/* Set arg count, init pointers to vector and string tables. */
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* (size_t *) frame = argc;
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vp = (char **) (frame + sizeof(argc));
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sp = frame + string_off;
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/* Load the argument vector and strings. */
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for (ap= argv; *ap != NULL; ap++) {
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*vp++= (char *) (sp - frame);
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n= strlen(*ap) + 1;
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memcpy(sp, *ap, n);
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sp+= n;
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}
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*vp++= NULL;
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/* Load the environment vector and strings. */
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for (ep= envp; *ep != NULL; ep++) {
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*vp++= (char *) (sp - frame);
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n= strlen(*ep) + 1;
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memcpy(sp, *ep, n);
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sp+= n;
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}
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*vp++= NULL;
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/* Padding. */
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while (sp < frame + frame_size) *sp++= 0;
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/* We can finally make the system call. */
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m.m1_i1 = strlen(path) + 1;
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m.m1_i2 = frame_size;
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m.m1_p1 = (char *) path;
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m.m1_p2 = frame;
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/* Clear unused fields */
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m.m1_i3 = 0;
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m.m1_p3 = NULL;
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(void) _syscall(PM_PROC_NR, EXEC, &m);
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/* Failure, return the memory used for the frame and exit. */
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(void) sbrk(-frame_size);
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return -1;
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}
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