util: Add handling code to safely read and write arrays

There was a missing code for handling the null character
so that it doesn't exceed the array size when reading and storing strings.
The code has been modified to handle the array safely.
To avoid overflow issue, this is necessary.

Change-Id: Ib75301a07906391c57fb739ef3399ff211cd1503
Signed-off-by: Yunhee Seo <yuni.seo@samsung.com>

diff --git a/src/util.c b/src/util.c
index 6ab94d3472cb908ab3f770208a66e54ce487208d..9758e64ce17172cc73f744626c7932c67b78d51d 100644 (file)
--- a/src/util.c
+++ b/src/util.c
@@ -30,19 +30,18 @@ static int sysfs_read_buf(char *path, char *buf, int len)
 
        fd = open(path, O_RDONLY);
        if (fd == -1)
-               return -ENOENT;
+               return -errno;
 
        r = read(fd, buf, len);
        close(fd);
 
-       if ((r < 0) || (r > len))
+       if ((r < 0) || (r >= len)) {
+               buf[0] = '\0';
                return -EIO;
+       }
 
-       /* Replace '\n' with space (ascii code is 32) */
-       buf[strcspn(buf, "\n")] = (char)32;
        buf[r] = '\0';
-
-       return 0;
+       return r;
 }
 
 int sysfs_write_buf(char *path, char *buf)
@@ -54,7 +53,7 @@ int sysfs_write_buf(char *path, char *buf)
 
        fd = open(path, O_WRONLY);
        if (fd == -1)
-               return -ENOENT;
+               return -errno;
 
        w = write(fd, buf, strlen(buf));
        close(fd);
@@ -67,13 +66,13 @@ int sysfs_write_buf(char *path, char *buf)
 
 int sysfs_read_int(char *path, int *val)
 {
-       char buf[MAX_BUF_SIZE + 1];
+       char buf[MAX_BUF_SIZE];
        int r;
 
        if ((!path) || (!val))
                return -EINVAL;
 
-       r = sysfs_read_buf(path, buf, MAX_BUF_SIZE);
+       r = sysfs_read_buf(path, buf, sizeof(buf));
        if (r < 0)
                return r;
 
@@ -97,13 +96,13 @@ int sysfs_read_str(char *path, char *str, int len)
 
 int sysfs_write_int(char *path, int val)
 {
-       char buf[MAX_BUF_SIZE + 1];
+       char buf[MAX_BUF_SIZE];
        int w;
 
        if (!path)
                return -EINVAL;
 
-       snprintf(buf, MAX_BUF_SIZE, "%d", val);
+       snprintf(buf, sizeof(buf), "%d", val);
        w = sysfs_write_buf(path, buf);
        if (w < 0)
                return w;