Python/getcwd.c

   1
   2 /* Two PD getcwd() implementations.
   3    Author: Guido van Rossum, CWI Amsterdam, Jan 1991, <guido@cwi.nl>. */
   4
   5 #include <stdio.h>
   6 #include <errno.h>
   7
   8 #ifdef HAVE_GETWD
   9
  10 /* Version for BSD systems -- use getwd() */
  11
  12 #ifdef HAVE_SYS_PARAM_H
  13 #include <sys/param.h>
  14 #endif
  15
  16 #ifndef MAXPATHLEN
  17 #if defined(PATH_MAX) && PATH_MAX > 1024
  18 #define MAXPATHLEN PATH_MAX
  19 #else
  20 #define MAXPATHLEN 1024
  21 #endif
  22 #endif
  23
  24 extern char *getwd(char *);
  25
  26 char *
  27 getcwd(char *buf, int size)
  28 {
  29         char localbuf[MAXPATHLEN+1];
  30         char *ret;
  31
  32         if (size <= 0) {
  33                 errno = EINVAL;
  34                 return NULL;
  35         }
  36         ret = getwd(localbuf);
  37         if (ret != NULL && strlen(localbuf) >= (size_t)size) {
  38                 errno = ERANGE;
  39                 return NULL;
  40         }
  41         if (ret == NULL) {
  42                 errno = EACCES; /* Most likely error */
  43                 return NULL;
  44         }
  45         strncpy(buf, localbuf, size);
  46         return buf;
  47 }
  48
  49 #else /* !HAVE_GETWD */
  50
  51 /* Version for really old UNIX systems -- use pipe from pwd */
  52
  53 #ifndef PWD_CMD
  54 #define PWD_CMD "/bin/pwd"
  55 #endif
  56
  57 char *
  58 getcwd(char *buf, int size)
  59 {
  60         FILE *fp;
  61         char *p;
  62         int sts;
  63         if (size <= 0) {
  64                 errno = EINVAL;
  65                 return NULL;
  66         }
  67         if ((fp = popen(PWD_CMD, "r")) == NULL)
  68                 return NULL;
  69         if (fgets(buf, size, fp) == NULL || (sts = pclose(fp)) != 0) {
  70                 errno = EACCES; /* Most likely error */
  71                 return NULL;
  72         }
  73         for (p = buf; *p != '\n'; p++) {
  74                 if (*p == '\0') {
  75                         errno = ERANGE;
  76                         return NULL;
  77                 }
  78         }
  79         *p = '\0';
  80         return buf;
  81 }
  82
  83 #endif /* !HAVE_GETWD */