nano

commit fdd946c02cd1c7c5f04914f05540ced73ab5775e
parent 81e5b57d74adb3ae7ce0f88a9514600fee23714b
Author: Benno Schulenberg <bensberg@telfort.nl>
Date:   Wed, 30 Mar 2022 17:05:23 +0200

files: do not change to a higher directory when the working one is gone

When the working directory has been deleted from under nano's feet,
get_full_path() would move up in the directory tree until getcwd()
would succeed.  This meant that a filename that was specified on the
command line without any path (or with a relative path) would refer
to a different file than what the user intended.  Not good.

So, stop changing directories in get_full_path().  Use the realpath()
function with NULL as second parameter instead -- it has been part of
the POSIX standard since 2008, time enough for operating systems to
have caught up.

In the bargain, this saves seventy lines of complicated logic.

This fixes https://savannah.gnu.org/bugs/?62244.

Bug existed since version 2.0.0, commit 85e35e67.

Diffstat:
M
src/files.c
 | 
106
++++++++++++++-----------------------------------------------------------------

1 file changed, 18 insertions(+), 88 deletions(-)
diff --git a/src/files.c b/src/files.c
@@ -1345,106 +1345,36 @@ void do_execute(void)
  * absolute path (plus filename) when the path exists, and NULL when not. */
 char *get_full_path(const char *origpath)
 {
-	char *allocation, *here, *target, *last_slash;
-	char *just_filename = NULL;
-	int attempts = 0;
+	char *untilded, *target, *slash;
 	struct stat fileinfo;
-	bool path_only;
 
 	if (origpath == NULL)
 		return NULL;
 
-	allocation = nmalloc(PATH_MAX + 1);
-	here = getcwd(allocation, PATH_MAX + 1);
+	untilded = real_dir_from_tilde(origpath);
+	target = realpath(untilded, NULL);
+	slash = strrchr(untilded, '/');
 
-	/* If getting the current directory failed, go up one level and try again,
-	 * until we find an existing directory, and use that as the current one. */
-	while (here == NULL && attempts < 20) {
-		IGNORE_CALL_RESULT(chdir(".."));
-		here = getcwd(allocation, PATH_MAX + 1);
-		attempts++;
-	}
-
-	/* If we found a directory, make sure its path ends in a slash. */
-	if (here != NULL) {
-		if (strcmp(here, "/") != 0) {
-			here = nrealloc(here, strlen(here) + 2);
-			strcat(here, "/");
-		}
-	} else {
-		here = copy_of("");
-		free(allocation);
-	}
-
-	target = real_dir_from_tilde(origpath);
-
-	/* Determine whether the target path refers to a directory.  If statting
-	 * target fails, however, assume that it refers to a new, unsaved buffer. */
-	path_only = (stat(target, &fileinfo) != -1 && S_ISDIR(fileinfo.st_mode));
-
-	/* If the target is a directory, make sure its path ends in a slash. */
-	if (path_only) {
-		size_t length = strlen(target);
-
-		if (target[length - 1] != '/') {
-			target = nrealloc(target, length + 2);
-			strcat(target, "/");
-		}
-	}
-
-	last_slash = strrchr(target, '/');
-
-	/* If the target path does not contain a slash, then it is a bare filename
-	 * and must therefore be located in the working directory. */
-	if (last_slash == NULL) {
-		just_filename = target;
-		target = here;
-	} else {
-		/* If target contains a filename, separate the two. */
-		if (!path_only) {
-			just_filename = copy_of(last_slash + 1);
-			*(last_slash + 1) = '\0';
-		}
-
-		/* If we can't change to the target directory, give up.  Otherwise,
-		 * get the canonical path to this target directory. */
-		if (chdir(target) == -1) {
-			free(target);
-			target = NULL;
-		} else {
-			free(target);
-
-			allocation = nmalloc(PATH_MAX + 1);
-			target = getcwd(allocation, PATH_MAX + 1);
-
-			/* If we got a result, make sure it ends in a slash.
-			 * Otherwise, ensure that we return NULL. */
-			if (target != NULL) {
-				if (strcmp(target, "/") != 0) {
-					target = nrealloc(target, strlen(target) + 2);
-					strcat(target, "/");
-				}
-			} else {
-				path_only = TRUE;
-				free(allocation);
-			}
+	/* If realpath() returned NULL, try without the last component,
+	 * as this can be a file that does not exist yet. */
+	if (!target && slash && slash[1]) {
+		*slash = '\0';
+		target = realpath(untilded, NULL);
 
-			/* Finally, go back to where we were before.  We don't check
-			 * for an error, since we can't do anything if we get one. */
-			IGNORE_CALL_RESULT(chdir(here));
+		/* Upon success, re-add the last component of the original path. */
+		if (target) {
+			target = nrealloc(target, strlen(target) + strlen(slash + 1) + 1);
+			strcat(target, slash + 1);
 		}
-
-		free(here);
 	}
 
-	/* If we were given more than a bare path, concatenate the target path
-	 * with the filename portion to get the full, absolute file path. */
-	if (!path_only && target != NULL) {
-		target = nrealloc(target, strlen(target) + strlen(just_filename) + 1);
-		strcat(target, just_filename);
+	/* Ensure that a directory path ends with a slash. */
+	if (target && stat(target, &fileinfo) == 0 && S_ISDIR(fileinfo.st_mode)) {
+		target = nrealloc(target, strlen(target) + 2);
+		strcat(target, "/");
 	}
 
-	free(just_filename);
+	free(untilded);
 
 	return target;
 }