From 2e918d33be152c1a57ffb3ff53e344cafb161a8c Mon Sep 17 00:00:00 2001
From: Tavian Barnes <tavianator@tavianator.com>
Date: Tue, 21 Sep 2021 18:47:28 -0400
Subject: util: New xfopen() utility

And use it to pass O_CLOEXEC to all FILE*'s, so the files opened for
-fprint etc. don't get passed to the programs run by -exec etc.
---
 color.c |  2 +-
 mtab.c  |  2 +-
 parse.c |  2 +-
 util.c  | 45 +++++++++++++++++++++++++++++++++++++++++++++
 util.h  | 10 ++++++++++
 5 files changed, 58 insertions(+), 3 deletions(-)

diff --git a/color.c b/color.c
index 509e646..09070f2 100644
--- a/color.c
+++ b/color.c
@@ -526,7 +526,7 @@ CFILE *cfopen(const char *path, const struct colors *colors) {
 		return NULL;
 	}
 
-	cfile->file = fopen(path, "wb");
+	cfile->file = xfopen(path, O_WRONLY | O_CREAT | O_TRUNC | O_CLOEXEC);
 	if (!cfile->file) {
 		cfclose(cfile);
 		return NULL;
diff --git a/mtab.c b/mtab.c
index 91a40aa..cb6a59a 100644
--- a/mtab.c
+++ b/mtab.c
@@ -162,7 +162,7 @@ struct bfs_mtab *bfs_mtab_parse() {
 
 #elif BFS_MNTTAB
 
-	FILE *file = fopen(MNTTAB, "r");
+	FILE *file = xfopen(MNTTAB, O_RDONLY | O_CLOEXEC);
 	if (!file) {
 		error = errno;
 		goto fail;
diff --git a/parse.c b/parse.c
index ad8e89c..98e7dbb 100644
--- a/parse.c
+++ b/parse.c
@@ -1278,7 +1278,7 @@ static struct expr *parse_files0_from(struct parser_state *state, int arg1, int
 	if (strcmp(from, "-") == 0) {
 		file = stdin;
 	} else {
-		file = fopen(from, "rb");
+		file = xfopen(from, O_RDONLY | O_CLOEXEC);
 	}
 	if (!file) {
 		parse_error(state, "${blu}%s${rs} ${bld}%s${rs}: %m.\n", arg, from);
diff --git a/util.c b/util.c
index d913b7d..728f962 100644
--- a/util.c
+++ b/util.c
@@ -16,6 +16,7 @@
 
 #include "util.h"
 #include "dstring.h"
+#include <assert.h>
 #include <errno.h>
 #include <fcntl.h>
 #include <langinfo.h>
@@ -426,3 +427,47 @@ char *xgetdelim(FILE *file, char delim) {
 		return NULL;
 	}
 }
+
+FILE *xfopen(const char *path, int flags) {
+	char mode[4];
+
+	switch (flags & O_ACCMODE) {
+	case O_RDONLY:
+		strcpy(mode, "rb");
+		break;
+	case O_WRONLY:
+		strcpy(mode, "wb");
+		break;
+	case O_RDWR:
+		strcpy(mode, "r+b");
+		break;
+	default:
+		assert(!"Invalid access mode");
+		return NULL;
+	}
+
+	if (flags & O_APPEND) {
+		mode[0] = 'a';
+	}
+
+	int fd;
+	if (flags & O_CREAT) {
+		fd = open(path, flags, 0666);
+	} else {
+		fd = open(path, flags);
+	}
+
+	if (fd < 0) {
+		return NULL;
+	}
+
+	FILE *ret = fdopen(fd, mode);
+	if (!ret) {
+		int error = errno;
+		close(fd);
+		errno = error;
+		return NULL;
+	}
+
+	return ret;
+}
diff --git a/util.h b/util.h
index be38db5..ccac549 100644
--- a/util.h
+++ b/util.h
@@ -288,4 +288,14 @@ char *xconfstr(int name);
  */
 char *xgetdelim(FILE *file, char delim);
 
+/**
+ * fopen() variant that takes open() style flags.
+ *
+ * @param path
+ *         The path to open.
+ * @param flags
+ *         Flags to pass to open().
+ */
+FILE *xfopen(const char *path, int flags);
+
 #endif // BFS_UTIL_H
-- 
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