Fix adb device ip parsing

The parser assumed that its input was a NUL-terminated string, but it
was not the case: it is just the raw output of "adb devices ip route".

In practice, it was harmless, since the output always ended with '\n'
(which was replaced by '\0' on truncation), but it was incorrect
nonetheless.

Always write a '\0' at the end of the buffer, and explicitly parse as a
NUL-terminated string. For that purpose, avoid the error-prone
sc_str_truncate() util function.

app/src/adb/adb.c

@@ -446,7 +446,7 @@ sc_adb_get_device_ip(struct sc_intr *intr, const char *serial, unsigned flags) {
 
     // "adb shell ip route" output should contain only a few lines
     char buf[1024];
-    ssize_t r = sc_pipe_read_all_intr(intr, pid, pout, buf, sizeof(buf));
+    ssize_t r = sc_pipe_read_all_intr(intr, pid, pout, buf, sizeof(buf) - 1);
     sc_pipe_close(pout);
 
     bool ok = process_check_success_intr(intr, pid, "ip route", flags);
@@ -458,8 +458,8 @@ sc_adb_get_device_ip(struct sc_intr *intr, const char *serial, unsigned flags) {
         return NULL;
     }
 
-    assert((size_t) r <= sizeof(buf));
+    assert((size_t) r < sizeof(buf));
-    if (r == sizeof(buf) && buf[sizeof(buf) - 1] != '\0')  {
+    if (r == sizeof(buf) - 1)  {
         // The implementation assumes that the output of "ip route" fits in the
         // buffer in a single pass
         LOGW("Result of \"ip route\" does not fit in 1Kb. "
@@ -467,5 +467,8 @@ sc_adb_get_device_ip(struct sc_intr *intr, const char *serial, unsigned flags) {
         return NULL;
     }
 
-    return sc_adb_parse_device_ip_from_output(buf, r);
+    // It is parsed as a NUL-terminated string
+    buf[r] = '\0';
+
+    return sc_adb_parse_device_ip_from_output(buf);
 }

app/src/adb/adb_parser.c

@@ -7,7 +7,7 @@
 #include "util/str.h"
 
 static char *
-sc_adb_parse_device_ip_from_line(char *line, size_t len) {
+sc_adb_parse_device_ip_from_line(char *line) {
     // One line from "ip route" looks like:
     // "192.168.1.0/24 dev wlan0  proto kernel  scope link  src 192.168.1.x"
 
@@ -27,10 +27,12 @@ sc_adb_parse_device_ip_from_line(char *line, size_t len) {
     idx_ip += idx_dev_name;
 
     char *dev_name = &line[idx_dev_name];
-    sc_str_truncate(dev_name, len - idx_dev_name + 1, " \t");
+    size_t dev_name_len = strcspn(dev_name, " \t");
+    dev_name[dev_name_len] = '\0';
 
     char *ip = &line[idx_ip];
-    sc_str_truncate(ip, len - idx_ip + 1, " \t");
+    size_t ip_len = strcspn(ip, " \t");
+    ip[ip_len] = '\0';
 
     // Only consider lines where the device name starts with "wlan"
     if (strncmp(dev_name, "wlan", sizeof("wlan") - 1)) {
@@ -42,23 +44,28 @@ sc_adb_parse_device_ip_from_line(char *line, size_t len) {
 }
 
 char *
-sc_adb_parse_device_ip_from_output(char *buf, size_t buf_len) {
+sc_adb_parse_device_ip_from_output(char *str) {
     size_t idx_line = 0;
-    while (idx_line < buf_len && buf[idx_line] != '\0') {
+    while (str[idx_line] != '\0') {
-        char *line = &buf[idx_line];
+        char *line = &str[idx_line];
-        size_t len = sc_str_truncate(line, buf_len - idx_line, "\n");
+        size_t len = strcspn(line, "\n");
 
         // The same, but without any trailing '\r'
         size_t line_len = sc_str_remove_trailing_cr(line, len);
+        line[line_len] = '\0';
 
-        char *ip = sc_adb_parse_device_ip_from_line(line, line_len);
+        char *ip = sc_adb_parse_device_ip_from_line(line);
         if (ip) {
             // Found
             return ip;
         }
 
-        // The next line starts after the '\n' (replaced by `\0`)
+        idx_line += len;
-        idx_line += len + 1;
+
+        if (str[idx_line] != '\0') {
+            // The next line starts after the '\n'
+            idx_line += 1;
+        }
     }
 
     return NULL;

app/src/adb/adb_parser.h

@@ -8,9 +8,11 @@
 /**
  * Parse the ip from the output of `adb shell ip route`
  *
+ * The parameter must be a NUL-terminated string.
+ *
  * Warning: this function modifies the buffer for optimization purposes.
  */
 char *
-sc_adb_parse_device_ip_from_output(char *buf, size_t buf_len);
+sc_adb_parse_device_ip_from_output(char *str);
 
 #endif

app/tests/test_adb_parser.c

@@ -8,7 +8,7 @@ static void test_get_ip_single_line() {
     char ip_route[] = "192.168.1.0/24 dev wlan0  proto kernel  scope link  src "
                       "192.168.12.34\r\r\n";
 
-    char *ip = sc_adb_parse_device_ip_from_output(ip_route, sizeof(ip_route));
+    char *ip = sc_adb_parse_device_ip_from_output(ip_route);
     assert(ip);
     assert(!strcmp(ip, "192.168.12.34"));
     free(ip);
@@ -18,7 +18,7 @@ static void test_get_ip_single_line_without_eol() {
     char ip_route[] = "192.168.1.0/24 dev wlan0  proto kernel  scope link  src "
                       "192.168.12.34";
 
-    char *ip = sc_adb_parse_device_ip_from_output(ip_route, sizeof(ip_route));
+    char *ip = sc_adb_parse_device_ip_from_output(ip_route);
     assert(ip);
     assert(!strcmp(ip, "192.168.12.34"));
     free(ip);
@@ -28,7 +28,7 @@ static void test_get_ip_single_line_with_trailing_space() {
     char ip_route[] = "192.168.1.0/24 dev wlan0  proto kernel  scope link  src "
                       "192.168.12.34 \n";
 
-    char *ip = sc_adb_parse_device_ip_from_output(ip_route, sizeof(ip_route));
+    char *ip = sc_adb_parse_device_ip_from_output(ip_route);
     assert(ip);
     assert(!strcmp(ip, "192.168.12.34"));
     free(ip);
@@ -40,7 +40,7 @@ static void test_get_ip_multiline_first_ok() {
                       "10.0.0.0/24 dev rmnet  proto kernel  scope link  src "
                       "10.0.0.2\r\n";
 
-    char *ip = sc_adb_parse_device_ip_from_output(ip_route, sizeof(ip_route));
+    char *ip = sc_adb_parse_device_ip_from_output(ip_route);
     assert(ip);
     assert(!strcmp(ip, "192.168.1.2"));
     free(ip);
@@ -52,7 +52,7 @@ static void test_get_ip_multiline_second_ok() {
                       "192.168.1.0/24 dev wlan0  proto kernel  scope link  src "
                       "192.168.1.3\r\n";
 
-    char *ip = sc_adb_parse_device_ip_from_output(ip_route, sizeof(ip_route));
+    char *ip = sc_adb_parse_device_ip_from_output(ip_route);
     assert(ip);
     assert(!strcmp(ip, "192.168.1.3"));
     free(ip);
@@ -62,7 +62,15 @@ static void test_get_ip_no_wlan() {
     char ip_route[] = "192.168.1.0/24 dev rmnet  proto kernel  scope link  src "
                       "192.168.12.34\r\r\n";
 
-    char *ip = sc_adb_parse_device_ip_from_output(ip_route, sizeof(ip_route));
+    char *ip = sc_adb_parse_device_ip_from_output(ip_route);
+    assert(!ip);
+}
+
+static void test_get_ip_no_wlan_without_eol() {
+    char ip_route[] = "192.168.1.0/24 dev rmnet  proto kernel  scope link  src "
+                      "192.168.12.34";
+
+    char *ip = sc_adb_parse_device_ip_from_output(ip_route);
     assert(!ip);
 }
 
@@ -70,7 +78,7 @@ static void test_get_ip_truncated() {
     char ip_route[] = "192.168.1.0/24 dev rmnet  proto kernel  scope link  src "
                       "\n";
 
-    char *ip = sc_adb_parse_device_ip_from_output(ip_route, sizeof(ip_route));
+    char *ip = sc_adb_parse_device_ip_from_output(ip_route);
     assert(!ip);
 }
 
@@ -84,5 +92,6 @@ int main(int argc, char *argv[]) {
     test_get_ip_multiline_first_ok();
     test_get_ip_multiline_second_ok();
     test_get_ip_no_wlan();
+    test_get_ip_no_wlan_without_eol();
     test_get_ip_truncated();
 }