unix: make uv_exepath(size=0) return UV_EINVAL

Make the behavior of a call to uv_exepath() with a size argument of zero
consistent with the Windows implementation where it returns UV_EINVAL.

PR-URL: https://github.com/libuv/libuv/pull/104
Reviewed-By: Saúl Ibarra Corretgé <saghul@gmail.com>

src/unix/aix.c

@@ -294,7 +294,7 @@ int uv_exepath(char* buffer, size_t* size) {
   int fd;
   char **argv;
 
-  if ((buffer == NULL) || (size == NULL))
+  if (buffer == NULL || size == NULL || *size == 0)
     return -EINVAL;
 
   snprintf(pp, sizeof(pp), "/proc/%lu/psinfo", (unsigned long) getpid());

src/unix/darwin.c

@@ -70,7 +70,7 @@ int uv_exepath(char* buffer, size_t* size) {
   char* path;
   char* fullpath;
 
-  if (buffer == NULL || size == NULL)
+  if (buffer == NULL || size == NULL || *size == 0)
     return -EINVAL;
 
   usize = *size;

src/unix/freebsd.c

@@ -78,7 +78,7 @@ int uv_exepath(char* buffer, size_t* size) {
   int mib[4];
   size_t cb;
 
-  if (buffer == NULL || size == NULL)
+  if (buffer == NULL || size == NULL || *size == 0)
     return -EINVAL;
 
 #ifdef __DragonFly__

src/unix/linux-core.c

@@ -378,7 +378,7 @@ void uv_loadavg(double avg[3]) {
 int uv_exepath(char* buffer, size_t* size) {
   ssize_t n;
 
-  if (buffer == NULL || size == NULL)
+  if (buffer == NULL || size == NULL || *size == 0)
     return -EINVAL;
 
   n = readlink("/proc/self/exe", buffer, *size - 1);

src/unix/netbsd.c

@@ -83,7 +83,7 @@ int uv_exepath(char* buffer, size_t* size) {
   size_t cb;
   pid_t mypid;
 
-  if (buffer == NULL || size == NULL)
+  if (buffer == NULL || size == NULL || *size == 0)
     return -EINVAL;
 
   mypid = getpid();

src/unix/openbsd.c

@@ -85,7 +85,7 @@ int uv_exepath(char* buffer, size_t* size) {
   pid_t mypid;
   int err;
 
-  if (buffer == NULL || size == NULL)
+  if (buffer == NULL || size == NULL || *size == 0)
     return -EINVAL;
 
   mypid = getpid();

src/unix/sunos.c

@@ -300,7 +300,7 @@ int uv_exepath(char* buffer, size_t* size) {
   ssize_t res;
   char buf[128];
 
-  if (buffer == NULL || size == NULL)
+  if (buffer == NULL || size == NULL || *size == 0)
     return -EINVAL;
 
   snprintf(buf, sizeof(buf), "/proc/%lu/path/a.out", (unsigned long) getpid());

test/test-get-currentexe.c

@@ -61,5 +61,9 @@ TEST_IMPL(get_currentexe) {
   r = uv_exepath(buffer, NULL);
   ASSERT(r == UV_EINVAL);
 
+  size = 0;
+  r = uv_exepath(buffer, &size);
+  ASSERT(r == UV_EINVAL);
+
   return 0;
 }