From 1b2018e9219400735a340837659b3f4e201618e9 Mon Sep 17 00:00:00 2001 From: Benno Schulenberg Date: Sun, 12 May 2019 10:36:15 +0200 Subject: [PATCH] files: check for writability by the access bits, not by trying to append Trying to append does not work on a fifo, and we'd like to be able to open a fifo again. Also, the append test causes a close event for the given file at the moment of opening it, which makes using 'inotify' for waiting for this file to be closed useless. Commit f8f90272 added the append test, but the original request (https://lists.gnu.org/archive/html/info-nano/2009-05/msg00000.html by Damien Joldersma) asked only for a warning when the user did not have enough privileges to write to the file. So, drop the append test and just check the access bits. This fixes https://bugs.debian.org/583196 and fixes https://savannah.gnu.org/bugs/?29312. --- src/files.c | 37 +------------------------------------ 1 file changed, 1 insertion(+), 36 deletions(-) diff --git a/src/files.c b/src/files.c index 0bdfacf1..c3aba679 100644 --- a/src/files.c +++ b/src/files.c @@ -698,41 +698,6 @@ bool close_buffer(void) } #endif /* ENABLE_MULTIBUFFER */ -/* Do a quick permissions check by verifying whether the file is appendable. - * Err on the side of permissiveness (reporting TRUE when it might be wrong) - * to not fluster users editing on odd filesystems by printing incorrect - * warnings. */ -int is_file_writable(const char *filename) -{ - char *full_filename; - struct stat fileinfo; - int fd; - FILE *f; - bool result = TRUE; - - if (ISSET(VIEW_MODE)) - return TRUE; - - full_filename = get_full_path(filename); - - /* If the absolute path is unusable, use the given relative one. */ - if (full_filename == NULL || stat(full_filename, &fileinfo) == -1) - full_filename = mallocstrcpy(NULL, filename); - - if ((fd = open(full_filename, O_WRONLY | O_CREAT | O_APPEND, S_IRUSR | - S_IWUSR | S_IRGRP | S_IWGRP | S_IROTH | S_IWOTH)) == -1) - result = FALSE; - else if ((f = fdopen(fd, "a")) == NULL) { - result = FALSE; - close(fd); - } else - fclose(f); - - free(full_filename); - - return result; -} - /* Encode any NUL bytes in the given line of text, which is of length buf_len, * and return a dynamically allocated copy of the resultant string. */ char *encode_data(char *buf, size_t buf_len) @@ -879,7 +844,7 @@ void read_file(FILE *f, int fd, const char *filename, bool undoable) fclose(f); if (fd > 0 && !undoable) { close(fd); - writable = is_file_writable(filename); + writable = (ISSET(VIEW_MODE) || access(filename, W_OK) == 0); } /* If the file ended with newline, or it was entirely empty, make the