runtime: Always use link target for /proc/self/exe

src/runtime.c

@@ -212,7 +212,7 @@ mkdir_p(const char* const path)
 }
 
 void
-print_help(const char *appimage_path)
+print_help(const char *appimage_fullpath)
 {
  // TODO: "--appimage-list List content from embedded filesystem image\n"
  fprintf(stderr,
@@ -244,27 +244,19 @@ print_help(const char *appimage_path)
  " and is neither moved nor renamed, the application contained inside this\n"
  " AppImage to store its data in this directory rather than in your home\n"
  " directory\n"
- , appimage_path);
+ , appimage_fullpath);
 }
 
 void
-portable_option(const char *arg, const char *appimage_path, const char *name)
+portable_option(const char *arg, const char *appimage_fullpath, const char *name)
 {
  char option[32];
  sprintf(option, "appimage-portable-%s", name);
 
  if (arg && strcmp(arg, option)==0) {
  char portable_dir[PATH_MAX];
- char fullpath[PATH_MAX];
 
- ssize_t length = readlink(appimage_path, fullpath, sizeof(fullpath));
- if (length < 0) {
- fprintf(stderr, "Error getting realpath for %s\n", appimage_path);
- exit(EXIT_FAILURE);
- }
- fullpath[length] = '\0';
-
- sprintf(portable_dir, "%s.%s", fullpath, name);
+ sprintf(portable_dir, "%s.%s", appimage_fullpath, name);
  if (!mkdir(portable_dir, S_IRWXU))
  fprintf(stderr, "Portable %s directory created at %s\n", name, portable_dir);
  else
@@ -536,7 +528,15 @@ int main(int argc, char *argv[]) {
  * functionality specifically for builds used by appimaged.
  */
  if (getenv("TARGET_APPIMAGE") == NULL) {
- strcpy(appimage_path, "/proc/self/exe");
+ // for some reason, `fopen("/proc/self/exe", "rb")` tries to open
+ // the dynamic linker when running under gcompat, even though `readlink()`
+ // gives the right result, so use `readlink()` here
+ ssize_t len = readlink("/proc/self/exe", appimage_path, sizeof(appimage_path));
+ if (len < 0) {
+ perror("Failed to obtain AppImage path");
+ exit(EXIT_EXECERROR);
+ }
+ appimage_path[len] = '\0';
  strcpy(argv0_path, argv[0]);
  } else {
  strcpy(appimage_path, getenv("TARGET_APPIMAGE"));
@@ -577,6 +577,24 @@ int main(int argc, char *argv[]) {
 #endif
  }
 
+ // calculate full path of AppImage
+ char appimage_fullpath[PATH_MAX];
+
+ if(getenv("TARGET_APPIMAGE") == NULL) {
+ // If we are operating on this file itself, then we've already
+ // expanded the symlink at `/proc/self/exe` in order to work
+ // around the issue with gcompat described above
+ strcpy(appimage_fullpath, appimage_path);
+ } else {
+ char* abspath = realpath(appimage_path, NULL);
+ if (abspath == NULL) {
+ perror("Failed to obtain realpath for $TARGET_APPIMAGE");
+ exit(EXIT_EXECERROR);
+ }
+ strcpy(appimage_fullpath, abspath);
+ free(abspath);
+ }
+
  // temporary directories are required in a few places
  // therefore we implement the detection of the temp base dir at the top of the code to avoid redundancy
  char temp_base[PATH_MAX] = P_tmpdir;
@@ -599,16 +617,7 @@ int main(int argc, char *argv[]) {
 
  /* Print the help and then exit */
  if(arg && strcmp(arg,"appimage-help")==0) {
- char fullpath[PATH_MAX];
-
- ssize_t length = readlink(appimage_path, fullpath, sizeof(fullpath));
- if (length < 0) {
- fprintf(stderr, "Error getting realpath for %s\n", appimage_path);
- exit(EXIT_EXECERROR);
- }
- fullpath[length] = '\0';
-
- print_help(fullpath);
+ print_help(appimage_fullpath);
  exit(0);
  }
 
@@ -642,28 +651,6 @@ int main(int argc, char *argv[]) {
  exit(0);
  }
 
- // calculate full path of AppImage
- int length;
- char fullpath[PATH_MAX];
-
- if(getenv("TARGET_APPIMAGE") == NULL) {
- // If we are operating on this file itself
- ssize_t len = readlink(appimage_path, fullpath, sizeof(fullpath));
- if (len < 0) {
- perror("Failed to obtain absolute path");
- exit(EXIT_EXECERROR);
- }
- fullpath[len] = '\0';
- } else {
- char* abspath = realpath(appimage_path, NULL);
- if (abspath == NULL) {
- perror("Failed to obtain absolute path");
- exit(EXIT_EXECERROR);
- }
- strcpy(fullpath, abspath);
- free(abspath);
- }
-
  if (getenv("APPIMAGE_EXTRACT_AND_RUN") != NULL || (arg && strcmp(arg, "appimage-extract-and-run") == 0)) {
  char* hexlified_digest = NULL;
 
@@ -727,7 +714,7 @@ int main(int argc, char *argv[]) {
  new_argv[new_argc] = NULL;
 
  /* Setting some environment variables that the app "inside" might use */
- setenv("APPIMAGE", fullpath, 1);
+ setenv("APPIMAGE", appimage_fullpath, 1);
  setenv("ARGV0", argv0_path, 1);
  setenv("APPDIR", prefix, 1);
 
@@ -785,8 +772,8 @@ int main(int argc, char *argv[]) {
  exit(0);
  }
 
- portable_option(arg, appimage_path, "home");
- portable_option(arg, appimage_path, "config");
+ portable_option(arg, appimage_fullpath, "home");
+ portable_option(arg, appimage_fullpath, "config");
 
  // If there is an argument starting with appimage- (but not appimage-mount which is handled further down)
  // then stop here and print an error message
@@ -908,23 +895,23 @@ int main(int argc, char *argv[]) {
  }
 
  /* Setting some environment variables that the app "inside" might use */
- setenv( "APPIMAGE", fullpath, 1 );
+ setenv( "APPIMAGE", appimage_fullpath, 1 );
  setenv( "ARGV0", argv0_path, 1 );
  setenv( "APPDIR", mount_dir, 1 );
 
  char portable_home_dir[PATH_MAX];
  char portable_config_dir[PATH_MAX];
 
  /* If there is a directory with the same name as the AppImage plus ".home", then export $HOME */
- strcpy (portable_home_dir, fullpath);
+ strcpy (portable_home_dir, appimage_fullpath);
  strcat (portable_home_dir, ".home");
  if(is_writable_directory(portable_home_dir)){
  fprintf(stderr, "Setting $HOME to %s\n", portable_home_dir);
  setenv("HOME",portable_home_dir,1);
  }
 
  /* If there is a directory with the same name as the AppImage plus ".config", then export $XDG_CONFIG_HOME */
- strcpy (portable_config_dir, fullpath);
+ strcpy (portable_config_dir, appimage_fullpath);
  strcat (portable_config_dir, ".config");
  if(is_writable_directory(portable_config_dir)){
  fprintf(stderr, "Setting $XDG_CONFIG_HOME to %s\n", portable_config_dir);