minix/lib/libc/sys/execve.c

   1 /* execve() - basic program execution call */
   2
   3 #include <sys/cdefs.h>
   4 #include "namespace.h"
   5 #include <lib.h>
   6
   7 #include <unistd.h>
   8 #include <string.h>
   9 #include <stddef.h>
  10 #include <minix/param.h>
  11 #include <sys/exec_elf.h>
  12 #include <sys/exec.h>
  13
  14 int execve(const char *path, char * const *argv, char * const *envp)
  15 {
  16         message m;
  17         size_t frame_size = 0;  /* Size of the new initial stack. */
  18         int argc = 0;           /* Argument count. */
  19         int envc = 0;           /* Environment count */
  20         char overflow = 0;      /* No overflow yet. */
  21         char *frame;
  22         struct ps_strings *psp;
  23         int vsp = 0;    /* (virtual) Stack pointer in new address space. */
  24
  25         minix_stack_params(path, argv, envp, &frame_size, &overflow,
  26                 &argc, &envc);
  27
  28         /* The party is off if there is an overflow. */
  29         if (overflow) {
  30                 errno = E2BIG;
  31                 return -1;
  32         }
  33
  34         /* Allocate space for the stack frame. */
  35         if ((frame = (char *) sbrk(frame_size)) == (char *) -1) {
  36                 errno = E2BIG;
  37                 return -1;
  38         }
  39
  40         minix_stack_fill(path, argc, argv, envc, envp, frame_size, frame,
  41                 &vsp, &psp);
  42
  43         /* Clear unused message fields */
  44         memset(&m, 0, sizeof(m));
  45
  46         /* We can finally make the system call. */
  47         m.m_lc_pm_exec.name = (vir_bytes)path;
  48         m.m_lc_pm_exec.namelen = strlen(path) + 1;
  49         m.m_lc_pm_exec.frame = (vir_bytes)frame;
  50         m.m_lc_pm_exec.framelen = frame_size;
  51         m.m_lc_pm_exec.ps_str = (vir_bytes)(vsp + ((char *)psp - frame));
  52
  53         (void) _syscall(PM_PROC_NR, PM_EXEC, &m);
  54
  55         /* Failure, return the memory used for the frame and exit. */
  56         (void) sbrk(-frame_size);
  57
  58         return -1;
  59 }