lib: Add functions to ease pseudo fs read/write
This adds SAFE_FILE_SCANF() and SAFE_FILE_PRINTF()
safe functions that operate like scanf and printf
but works with a path instead of the FILE pointer.
The file is opened and closed automatically and
all possible error conditions are handled. With
this we can reduce the number of fopen, fscanf, fclose
sequencies (with possibly incomplete error handling).
This also adds SAFE_CP() which is intended replacement
for system("cp ...") code.
Signed-off-by: Cyril Hrubis <chrubis@suse.cz>
diff --git a/lib/safe_file_ops.c b/lib/safe_file_ops.c
new file mode 100644
index 0000000..b1b11f3
--- /dev/null
+++ b/lib/safe_file_ops.c
@@ -0,0 +1,156 @@
+/*
+ * Copyright (C) 2012 Cyril Hrubis chrubis@suse.cz
+ *
+ * This program is free software; you can redistribute it and/or modify it
+ * under the terms of version 2 of the GNU General Public License as
+ * published by the Free Software Foundation.
+ *
+ * This program is distributed in the hope that it would be useful, but
+ * WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.
+ *
+ * Further, this software is distributed without any warranty that it is
+ * free of the rightful claim of any third person regarding infringement
+ * or the like. Any license provided herein, whether implied or
+ * otherwise, applies only to this software file. Patent licenses, if
+ * any, provided herein do not apply to combinations of this program with
+ * other software, or any other product whatsoever.
+ *
+ * You should have received a copy of the GNU General Public License along
+ * with this program; if not, write the Free Software Foundation, Inc.,
+ * 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA.
+ */
+
+#include <stdarg.h>
+#include <stdio.h>
+
+#include "safe_file_ops.h"
+
+/*
+ * Count number of expected assigned conversions. Any conversion starts with '%'.
+ * The '%%' matches % and no assigment is done. The %*x matches as x would do but
+ * the assigment is supressed.
+ *
+ * NOTE: This is not 100% correct for complex scanf strings, but will do for
+ * all of our intended usage.
+ */
+static int count_scanf_conversions(const char *fmt)
+{
+ unsigned int cnt = 0;
+ int flag = 0;
+
+ while (*fmt) {
+ switch (*fmt) {
+ case '%':
+ if (flag) {
+ cnt--;
+ flag = 0;
+ } else {
+ flag = 1;
+ cnt++;
+ }
+ break;
+ case '*':
+ if (flag) {
+ cnt--;
+ flag = 0;
+ }
+ break;
+ default:
+ flag = 0;
+ }
+
+ fmt++;
+ }
+
+ return cnt;
+}
+
+void safe_file_scanf(const char *file, const int lineno,
+ void (*cleanup_fn)(void),
+ const char *path, const char *fmt, ...)
+{
+ va_list va;
+ FILE *f;
+ int exp_convs, ret;
+
+ f = fopen(path, "r");
+
+ if (f == NULL) {
+ tst_brkm(TBROK | TERRNO, cleanup_fn,
+ "Failed to open FILE '%s' for reading at %s:%d",
+ path, file, lineno);
+ }
+
+ exp_convs = count_scanf_conversions(fmt);
+
+ va_start(va, fmt);
+ ret = vfscanf(f, fmt, va);
+ va_end(va);
+
+ if (ret == EOF) {
+ tst_brkm(TBROK, cleanup_fn,
+ "The FILE '%s' ended prematurely at %s:%d",
+ path, file, lineno);
+ }
+
+ if (ret != exp_convs) {
+ tst_brkm(TBROK, cleanup_fn,
+ "Expected %i conversions got %i FILE '%s' at %s:%d",
+ exp_convs, ret, path, file, lineno);
+ }
+
+}
+
+
+void safe_file_printf(const char *file, const int lineno,
+ void (*cleanup_fn)(void),
+ const char *path, const char *fmt, ...)
+{
+ va_list va;
+ FILE *f;
+
+ f = fopen(path, "w");
+
+ if (f == NULL) {
+ tst_brkm(TBROK | TERRNO, cleanup_fn,
+ "Failed to open FILE '%s' for writing at %s:%d",
+ path, file, lineno);
+ }
+
+ va_start(va, fmt);
+
+ if (vfprintf(f, fmt, va) < 0) {
+ tst_brkm(TBROK, cleanup_fn,
+ "Failed to print to FILE '%s' at %s:%d",
+ path, file, lineno);
+ }
+
+ va_end(va);
+
+ if (fclose(f)) {
+ tst_brkm(TBROK | TERRNO, cleanup_fn,
+ "Failed to close FILE '%s' at %s:%d",
+ path, file, lineno);
+ }
+}
+
+//TODO: C implementation? better error condition reporting?
+void safe_cp(const char *file, const int lineno,
+ void (*cleanup_fn)(void),
+ const char *src, const char *dst)
+{
+ size_t len = strlen(src) + strlen(dst) + 16;
+ char buf[len];
+ int ret;
+
+ snprintf(buf, sizeof(buf), "cp \"%s\" \"%s\"", src, dst);
+
+ ret = system(buf);
+
+ if (ret) {
+ tst_brkm(TBROK, cleanup_fn,
+ "Failed to copy '%s' to '%s' at %s:%d",
+ src, dst, file, lineno);
+ }
+}