getpwd.c revision 1.1
1/* getpwd.c - get the working directory */ 2 3/* 4 5@deftypefn Supplemental char* getpwd (void) 6 7Returns the current working directory. This implementation caches the 8result on the assumption that the process will not call @code{chdir} 9between calls to @code{getpwd}. 10 11@end deftypefn 12 13*/ 14 15#ifdef HAVE_CONFIG_H 16#include "config.h" 17#endif 18 19#include <sys/types.h> 20 21#include <errno.h> 22#ifndef errno 23extern int errno; 24#endif 25 26#ifdef HAVE_STDLIB_H 27#include <stdlib.h> 28#endif 29#ifdef HAVE_UNISTD_H 30#include <unistd.h> 31#endif 32#ifdef HAVE_SYS_PARAM_H 33#include <sys/param.h> 34#endif 35#if HAVE_SYS_STAT_H 36#include <sys/stat.h> 37#endif 38#if HAVE_LIMITS_H 39#include <limits.h> 40#endif 41 42#include "libiberty.h" 43 44/* Virtually every UN*X system now in common use (except for pre-4.3-tahoe 45 BSD systems) now provides getcwd as called for by POSIX. Allow for 46 the few exceptions to the general rule here. */ 47 48#if !defined(HAVE_GETCWD) && defined(HAVE_GETWD) 49/* Prototype in case the system headers doesn't provide it. */ 50extern char *getwd (); 51#define getcwd(buf,len) getwd(buf) 52#endif 53 54#ifdef MAXPATHLEN 55#define GUESSPATHLEN (MAXPATHLEN + 1) 56#else 57#define GUESSPATHLEN 100 58#endif 59 60#if !(defined (VMS) || (defined(_WIN32) && !defined(__CYGWIN__))) 61 62/* Get the working directory. Use the PWD environment variable if it's 63 set correctly, since this is faster and gives more uniform answers 64 to the user. Yield the working directory if successful; otherwise, 65 yield 0 and set errno. */ 66 67char * 68getpwd (void) 69{ 70 static char *pwd; 71 static int failure_errno; 72 73 char *p = pwd; 74 size_t s; 75 struct stat dotstat, pwdstat; 76 77 if (!p && !(errno = failure_errno)) 78 { 79 if (! ((p = getenv ("PWD")) != 0 80 && *p == '/' 81 && stat (p, &pwdstat) == 0 82 && stat (".", &dotstat) == 0 83 && dotstat.st_ino == pwdstat.st_ino 84 && dotstat.st_dev == pwdstat.st_dev)) 85 86 /* The shortcut didn't work. Try the slow, ``sure'' way. */ 87 for (s = GUESSPATHLEN; !getcwd (p = XNEWVEC (char, s), s); s *= 2) 88 { 89 int e = errno; 90 free (p); 91#ifdef ERANGE 92 if (e != ERANGE) 93#endif 94 { 95 errno = failure_errno = e; 96 p = 0; 97 break; 98 } 99 } 100 101 /* Cache the result. This assumes that the program does 102 not invoke chdir between calls to getpwd. */ 103 pwd = p; 104 } 105 return p; 106} 107 108#else /* VMS || _WIN32 && !__CYGWIN__ */ 109 110#ifndef MAXPATHLEN 111#define MAXPATHLEN 255 112#endif 113 114char * 115getpwd (void) 116{ 117 static char *pwd = 0; 118 119 if (!pwd) 120 pwd = getcwd (XNEWVEC (char, MAXPATHLEN + 1), MAXPATHLEN + 1 121#ifdef VMS 122 , 0 123#endif 124 ); 125 return pwd; 126} 127 128#endif /* VMS || _WIN32 && !__CYGWIN__ */ 129