lib/setproctitle.c

   1 /*
   2  *  set process title for ps (from sendmail)
   3  *
   4  *  Clobbers argv of our main procedure so ps(1) will display the title.
   5  */
   6 #include <stdio.h>
   7 #include <stdlib.h>
   8 #include <string.h>
   9 #include <stdarg.h>
  10
  11 #include "setproctitle.h"
  12
  13 #ifndef SPT_BUFSIZE
  14 # define SPT_BUFSIZE     2048
  15 #endif
  16
  17 extern char **environ;
  18
  19 static char **argv0;
  20 static size_t argv_lth;
  21
  22 void initproctitle (int argc, char **argv)
  23 {
  24         int i;
  25         char **envp = environ;
  26
  27         /*
  28          * Move the environment so we can reuse the memory.
  29          * (Code borrowed from sendmail.)
  30          * WARNING: ugly assumptions on memory layout here;
  31          *          if this ever causes problems, #undef DO_PS_FIDDLING
  32          */
  33         for (i = 0; envp[i] != NULL; i++)
  34                 continue;
  35
  36         environ = malloc(sizeof(char *) * (i + 1));
  37         if (environ == NULL)
  38                 return;
  39
  40         for (i = 0; envp[i] != NULL; i++)
  41                 if ((environ[i] = strdup(envp[i])) == NULL)
  42                         return;
  43         environ[i] = NULL;
  44
  45         if (i > 0)
  46                 argv_lth = envp[i-1] + strlen(envp[i-1]) - argv[0];
  47         else
  48                 argv_lth = argv[argc-1] + strlen(argv[argc-1]) - argv[0];
  49         if (argv_lth > 1)
  50                 argv0 = argv;
  51 }
  52
  53 void setproctitle (const char *prog, const char *txt)
  54 {
  55         size_t i;
  56         char buf[SPT_BUFSIZE];
  57
  58         if (!argv0)
  59                 return;
  60
  61         if (strlen(prog) + strlen(txt) + 5 > SPT_BUFSIZE)
  62                 return;
  63
  64         sprintf(buf, "%s -- %s", prog, txt);
  65
  66         i = strlen(buf);
  67         if (i > argv_lth - 2) {
  68                 i = argv_lth - 2;
  69                 buf[i] = '\0';
  70         }
  71         memset(argv0[0], '\0', argv_lth);       /* clear the memory area */
  72         strcpy(argv0[0], buf);
  73
  74         argv0[1] = NULL;
  75 }