gri3-wm/libi3/get_exe_path.c

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#include <unistd.h>
#include <string.h>
#include <stdio.h>
#include <limits.h>
#include <stdlib.h>
#include <errno.h>
#include "libi3.h"
/*
* This function returns the absolute path to the executable it is running in.
*
* The implementation follows http://stackoverflow.com/a/933996/712014
*
* Returned value must be freed by the caller.
*/
char *get_exe_path(const char *argv0) {
size_t destpath_size = 1024;
size_t tmp_size = 1024;
char *destpath = smalloc(destpath_size);
char *tmp = smalloc(tmp_size);
#if defined(__linux__) || defined(__FreeBSD__) || defined(__FreeBSD_kernel__)
/* Linux and Debian/kFreeBSD provide /proc/self/exe */
#if defined(__linux__) || defined(__FreeBSD_kernel__)
const char *exepath = "/proc/self/exe";
#elif defined(__FreeBSD__)
const char *exepath = "/proc/curproc/file";
#endif
ssize_t linksize;
while ((linksize = readlink(exepath, destpath, destpath_size)) == (ssize_t)destpath_size) {
destpath_size = destpath_size * 2;
destpath = srealloc(destpath, destpath_size);
}
if (linksize != -1) {
/* readlink() does not NULL-terminate strings, so we have to. */
destpath[linksize] = '\0';
free(tmp);
return destpath;
}
#endif
/* argv[0] is most likely a full path if it starts with a slash. */
if (argv0[0] == '/') {
free(tmp);
free(destpath);
return sstrdup(argv0);
}
/* if argv[0] contains a /, prepend the working directory */
if (strchr(argv0, '/') != NULL) {
char *retgcwd;
while ((retgcwd = getcwd(tmp, tmp_size)) == NULL && errno == ERANGE) {
tmp_size = tmp_size * 2;
tmp = srealloc(tmp, tmp_size);
}
if (retgcwd != NULL) {
free(destpath);
sasprintf(&destpath, "%s/%s", tmp, argv0);
free(tmp);
return destpath;
}
}
/* Fall back to searching $PATH (or _CS_PATH in absence of $PATH). */
char *path = getenv("PATH");
if (path == NULL) {
/* _CS_PATH is typically something like "/bin:/usr/bin" */
while (confstr(_CS_PATH, tmp, tmp_size) > tmp_size) {
tmp_size = tmp_size * 2;
tmp = srealloc(tmp, tmp_size);
}
sasprintf(&path, ":%s", tmp);
} else {
path = strdup(path);
}
const char *component;
char *str = path;
while (1) {
if ((component = strtok(str, ":")) == NULL)
break;
str = NULL;
free(destpath);
sasprintf(&destpath, "%s/%s", component, argv0);
/* Of course this is not 100% equivalent to actually exec()ing the
* binary, but meh. */
if (access(destpath, X_OK) == 0) {
free(path);
free(tmp);
return destpath;
}
}
free(destpath);
free(path);
free(tmp);
/* Last resort: maybe its in /usr/bin? */
return sstrdup("/usr/bin/i3-nagbar");
}