[PATCH 3/3] handle return values of read, write and fgets

[manuel.f.zerpies at ww.stud.uni-erlangen.de]

From: Manuel Zerpies <manuel.f.zerpies at ww.stud.uni-erlangen.de>

Check the return values of read(), write() and fgets().

Signed-off-by: Manuel Zerpies <manuel.f.zerpies at ww.stud.uni-erlangen.de>
---
 applets/applet_tables.c |    5 ++++-
 applets/usage.c         |    7 +++++--
 libbb/lineedit.c        |    4 +++-
 libbb/xfuncs_printf.c   |    4 +++-
 4 files changed, 15 insertions(+), 5 deletions(-)

diff --git a/applets/applet_tables.c b/applets/applet_tables.c
index 152d5f4..ffd4a82 100644
--- a/applets/applet_tables.c
+++ b/applets/applet_tables.c
@@ -141,8 +141,11 @@ int main(int argc, char **argv)
 		line_old[0] = 0;
 		fp = fopen(argv[2], "r");
 		if (fp) {
-			fgets(line_old, sizeof(line_old), fp);
+			char *c = fgets(line_old, sizeof(line_old), fp);
 			fclose(fp);
+			if (c == NULL) {
+				return 1;
+			}
 		}
 		sprintf(line_new, "#define NUM_APPLETS %u\n", NUM_APPLETS);
 		if (strcmp(line_old, line_new) != 0) {
diff --git a/applets/usage.c b/applets/usage.c
index 94520ff..faa6b27 100644
--- a/applets/usage.c
+++ b/applets/usage.c
@@ -48,8 +48,11 @@ int main(void)
 	qsort(usage_array,
 		num_messages, sizeof(usage_array[0]),
 		compare_func);
-	for (i = 0; i < num_messages; i++)
-		write(STDOUT_FILENO, usage_array[i].usage, strlen(usage_array[i].usage) + 1);
+	for (i = 0; i < num_messages; i++) {
+		ssize_t r = write(STDOUT_FILENO, usage_array[i].usage, strlen(usage_array[i].usage) + 1);
+		if (r < 0)
+			return 1;
+	}
 
 	return 0;
 }
diff --git a/libbb/lineedit.c b/libbb/lineedit.c
index b89748a..356c7f1 100644
--- a/libbb/lineedit.c
+++ b/libbb/lineedit.c
@@ -2729,7 +2729,9 @@ int FAST_FUNC read_line_input(const char* prompt, char* command, int maxsize)
 {
 	fputs(prompt, stdout);
 	fflush_all();
-	fgets(command, maxsize, stdin);
+	char *c = fgets(command, maxsize, stdin);
+	if (c == NULL)
+		return 0;
 	return strlen(command);
 }
 
diff --git a/libbb/xfuncs_printf.c b/libbb/xfuncs_printf.c
index 29c963f..9c76fbb 100644
--- a/libbb/xfuncs_printf.c
+++ b/libbb/xfuncs_printf.c
@@ -590,8 +590,10 @@ void FAST_FUNC generate_uuid(uint8_t *buf)
 
 	i = open("/dev/urandom", O_RDONLY);
 	if (i >= 0) {
-		read(i, buf, 16);
+		ssize_t r = read(i, buf, 16);
 		close(i);
+		if (r < 0)
+			return;
 	}
 	/* Paranoia. /dev/urandom may be missing.
 	 * rand() is guaranteed to generate at least [0, 2^15) range,
-- 
1.7.0.4