From ca89d65513c57c6517d5190d33f0bbc690ba5d46 Mon Sep 17 00:00:00 2001
From: Bruce Hill <bruce@bruce-hill.com>
Date: Sat, 14 May 2022 16:01:37 -0400
Subject: Better error handling

---
 match.c | 46 +++++++++++++++++++++++++++++++++++++++++-----
 1 file changed, 41 insertions(+), 5 deletions(-)

(limited to 'match.c')

diff --git a/match.c b/match.c
index 86ae2bd..cb7918c 100644
--- a/match.c
+++ b/match.c
@@ -49,6 +49,13 @@ typedef struct match_ctx_s {
 static match_t *unused_matches = NULL;
 static match_t *in_use_matches = NULL;
 
+static void default_error_handler(pat_t *pat, const char *msg) {
+    (void)pat;
+    errx(EXIT_FAILURE, "%s", msg);
+}
+
+static bp_errhand_t error_handler = default_error_handler;
+
 #define MATCHES(...) (match_t*[]){__VA_ARGS__, NULL}
 
 __attribute__((hot, nonnull(1,2,3)))
@@ -56,6 +63,18 @@ static match_t *match(match_ctx_t *ctx, const char *str, pat_t *pat);
 __attribute__((returns_nonnull))
 static match_t *new_match(pat_t *pat, const char *start, const char *end, match_t *children[]);
 
+__attribute__((format(printf,2,3)))
+static inline void match_error(pat_t *pat, const char *fmt, ...)
+{
+    va_list args;
+    va_start(args, fmt);
+    char buf[256];
+    vsnprintf(buf, sizeof(buf)-1, fmt, args);
+    va_end(args);
+    if (error_handler)
+        error_handler(pat, buf);
+}
+
 static match_t *clone_match(match_t *m)
 {
     if (!m) return NULL;
@@ -207,7 +226,8 @@ static pat_t *_lookup_def(pat_t *defs, const char *name, size_t namelen)
                 return defs->args.def.meaning;
             defs = defs->args.def.next_def;
         } else {
-            errx(1, "Invalid pattern type in definitions");
+            match_error(defs, "Invalid pattern type in definitions");
+            return NULL;
         }
     }
     return NULL;
@@ -646,8 +666,10 @@ static match_t *match(match_ctx_t *ctx, const char *str, pat_t *pat)
             return NULL;
 
         pat_t *ref = lookup_ctx(ctx, pat->args.ref.name, pat->args.ref.len);
-        if (ref == NULL)
-            errx(EXIT_FAILURE, "Unknown identifier: '%.*s'", (int)pat->args.ref.len, pat->args.ref.name);
+        if (ref == NULL) {
+            match_error(pat, "Unknown pattern: '%.*s'", (int)pat->args.ref.len, pat->args.ref.name);
+            return NULL;
+        }
 
         if (ref->type == BP_LEFTRECURSION)
             return match(ctx, str, ref);
@@ -732,7 +754,7 @@ static match_t *match(match_ctx_t *ctx, const char *str, pat_t *pat)
         return new_match(pat, str, str, NULL);
     }
     default: {
-        errx(EXIT_FAILURE, "Unknown pattern type: %u", pat->type);
+        match_error(pat, "Unknown pattern type: %u", pat->type);
         return NULL;
     }
     }
@@ -830,7 +852,10 @@ bool next_match(match_t **m, const char *start, const char *end, pat_t *pat, pat
         pos = start;
     }
 
-    if (!pat) return false;
+    if (!pat) {
+        error_handler = default_error_handler;
+        return false;
+    }
 
     match_ctx_t ctx = {
         .cache = &(cache_t){0},
@@ -844,6 +869,17 @@ bool next_match(match_t **m, const char *start, const char *end, pat_t *pat, pat
     return *m != NULL;
 }
 
+//
+// Wrapper for next_match() that sets an error handler
+//
+bool next_match_safe(match_t **m, const char *start, const char *end, pat_t *pat, pat_t *defs, pat_t *skip, bool ignorecase, bp_errhand_t errhand)
+{
+    error_handler = errhand;
+    bool ret = next_match(m, start, end, pat, defs, skip, ignorecase);
+    error_handler = default_error_handler;
+    return ret;
+}
+
 //
 // Helper function to track state while doing a depth-first search.
 //
-- 
cgit v1.2.3