Make make_shim a little more user-friendly

1 files changed, 10 insertions, 10 deletions

diff --git a/tools/make_shim.c b/tools/make_shim.c
index e4019cf..c5b684e 100644
--- a/tools/make_shim.c
+++ b/tools/make_shim.c
@@ -54,11 +54,11 @@ size_t strrcspn(const char *s1, const char *s2) {
     return _s1 - s1;
 }
 
-#define RIP(errmsg) {       \
-    errno = EIO;            \
-    perror(errmsg);         \
-    if (file) fclose(file); \
-    return 1;               \
+#define RIP(errmsg) {            \
+    if (errno == 0) errno = EIO; \
+    perror(errmsg);              \
+    if (file) fclose(file);      \
+    return 1;                    \
 }
 
 int main(int argc, char * argv[]) {
@@ -95,7 +95,7 @@ int main(int argc, char * argv[]) {
     for (int arg_idx = optind; arg_idx < argc; arg_idx++) {
         FILE * file = fopen(argv[arg_idx], "r");
         if (file == NULL)
-            RIP("file io");
+            RIP("Unable to open file");
         while ((lineptr = fgets(line, sizeof(line), file)) != NULL) {
             unsigned short bank = 0;
             unsigned short pointer = 0;
@@ -115,18 +115,18 @@ int main(int argc, char * argv[]) {
             end = lineptr + strcspn(lineptr, " \t\n");
             symbol = end + strspn(end, " \t\n");
             if (!*symbol)
-                RIP("parse");
+                RIP("Declaration not in \"bank:addr Name\" format");
             *end = 0;
             addr_p = strchr(lineptr, ':');
             if (!addr_p)
-                RIP("parse");
+                RIP("Pointer not in bank:addr format");
             *addr_p++ = 0;
             pointer = strtoul(addr_p, &end, 16);
             if (pointer == 0 && end == addr_p)
-                RIP("parse");
+                RIP("Unable to parse symbol address");
             bank = strtoul(lineptr, &end, 16);
             if (bank == 0 && end == lineptr)
-                RIP("parse");
+                RIP("Unable to parse bank number");
 
             // Main loop
             const char * section = NULL;