simplify error-to-string interface

4 files changed, 53 insertions, 48 deletions

diff --git a/examples/conf.pom b/examples/conf.pom
index 0edc83f..ed37ed9 100644
--- a/examples/conf.pom
+++ b/examples/conf.pom
@@ -1,7 +1,7 @@
-[number]
+[number]p
 one = 1
 two = 2x"\?
-three = "3
+three j= "3
 is
 the
 	best"
diff --git a/examples/read_conf.c b/examples/read_conf.c
index 54a1e86..18802e3 100644
--- a/examples/read_conf.c
+++ b/examples/read_conf.c
@@ -8,12 +8,7 @@ int main(int argc, char **argv) {
 	pom_error *error;
 	pom_conf *conf = pom_load_path(argc >= 2 ? argv[1] : "conf.pom", &error);
 	if (!conf) {
-		char *string = pom_error_to_string(error);
-		for (char *s=string; *s; s++)
-			if (*s >= 'a' && *s <= 'z')
-				*s += 'A' - 'a';
-		printf("%s\n",string);
-		free(string);
+		pom_error_print(error);
 		free(error);
 		return EXIT_FAILURE;
 	}
diff --git a/pom.c b/pom.c
index 01d9efb..906e970 100644
--- a/pom.c
+++ b/pom.c
@@ -35,6 +35,9 @@ struct pom_error {
 	const char *file;
 	uint64_t line;
 	const char *message;
+	// only set for first error in error list.
+	// return value of pom_error_to_string
+	const char *string;
 };
 
 struct conf_item {
@@ -219,7 +222,7 @@ make_error(const char *file, uint64_t line, const char *fmt, ...) {
 		bad_fmt = true;
 		len = strlen(fmt);
 	}
-	pom_error *err = malloc(sizeof(pom_error) + len + 1);
+	pom_error *err = malloc(sizeof(pom_error) + len * 2 + strlen(file) + 48);
 	if (err) {
 		char *message = (char *)(err + 1);
 		if (bad_fmt) {
@@ -230,6 +233,17 @@ make_error(const char *file, uint64_t line, const char *fmt, ...) {
 		err->file = file;
 		err->line = line;
 		err->message = message;
+		char *string = strchr(message, '\0') + 1;
+		// no, clang, string will not overlap with message.
+		#if __GNUC__ >= 4
+		#pragma GCC diagnostic push
+		#pragma GCC diagnostic ignored "-Wrestrict"
+		#endif
+		sprintf(string, "Error:\n%s:%" PRIu64 ": %s\n", file, line, message);
+		#if __GNUC__ >= 4
+		#pragma GCC diagnostic pop
+		#endif
+		err->string = string;
 		err->next = NULL;
 	}
 	va_end(args_copy);
@@ -265,15 +279,8 @@ pom_error_message(const pom_error *error) {
 
 #ifndef POM_NO_STDIO
 void
-pom_error_print(const pom_error *error) {
-	if (!error) {
-		fprintf(stderr, "No error.\n");
-		return;
-	}
-	fprintf(stderr, "Error:\n");
-	for (; error; error = pom_error_next(error)) {
-		fprintf(stderr, "%s:%" PRIu64 ": %s\n", error->file, error->line, error->message);
-	}
+pom_error_print(pom_error *error) {
+	fputs(pom_error_to_string(error), stderr);
 }
 #endif
 
@@ -282,26 +289,13 @@ parser_out_of_memory(struct parser *parser) {
 	parser->out_of_memory = true;
 }
 
-char *
+const char *
 pom_error_to_string(pom_error *error) {
-	// first, calculate # of bytes we have to allocate for the string
-	size_t bytes_required = 16;
-	for (const pom_error *e = error; e; e = e->next)
-		bytes_required += strlen(e->file) + strlen(e->message) + 32;
-	char *string = malloc(bytes_required);
-	if (!string) return NULL;
-	if (!error) {
-		strcpy(string, "No error.");
-		return string;
-	}
-	char *s = string;
-	strcpy(s, "Error:\n");
-	s = strchr(s, 0);
-	for (const pom_error *e = error; e; e = e->next) {
-		sprintf(s, "%s:%" PRIu64 ": %s\n", e->file, e->line, e->message);
-		s = strchr(s, 0);
+	if (error) {
+		return error->string;
+	} else {
+		return "No error.\n";
 	}
-	return string;
 }
 
 static POM__MUST_USE_L bool parser_realloc_(struct parser *parser, void *ptr, size_t elem_size, size_t *pcapacity, size_t new_capacity) POM__MUST_USE_R;
@@ -1090,8 +1084,9 @@ pom_load(const char *filename,
 		set_error(error, out_of_memory);
 	} else if (parser->errors.count) {
 		if (error) {
-			// shouldn't overflow
-			size_t len = parser->errors.count * sizeof(pom_error) + parser->error_messages.count + strlen(filename) + 1;
+			// shouldn't realistically overflow given that we cut off at 1000 errors
+			size_t len = (parser->errors.count + 1) * (sizeof(pom_error) + strlen(filename) + 32)
+				+ parser->error_messages.count * 2 + 16;
 			// convert parser_errors to pom_error.
 			pom_error *errors = malloc(len);
 			if (errors) {
@@ -1107,7 +1102,18 @@ pom_load(const char *filename,
 					errors[i].line = parser_error->line;
 					errors[i].message = messages + parser_error->message;
 					errors[i].next = i == parser->errors.count - 1 ? NULL : &errors[i+1];
+					errors[i].string = NULL;
+				}
+				// create string containing all error messages
+				char *string = strchr(filename, '\0') + 1, *s = string;
+				strcpy(s, "Error:\n");
+				s = strchr(s, 0);
+				for (size_t i = 0; i < parser->errors.count; i++) {
+					const pom_error *e = &errors[i];
+					sprintf(s, "%s:%" PRIu64 ": %s\n", e->file, e->line, e->message);
+					s = strchr(s, 0);
 				}
+				errors->string = string;
 				*error = errors;
 			} else {
 				*error = parser->out_of_memory_error;
diff --git a/pom.h b/pom.h
index ea38a3d..9adb156 100644
--- a/pom.h
+++ b/pom.h
@@ -90,6 +90,11 @@ typedef struct pom_item {
 
 /// Load a configuration using a `read`-like function.
 ///
+/// Most of the time, you won't need this function:
+/// use \ref pom_load_file to load from a `FILE *`,
+/// \ref pom_load_path to load from a path,
+/// and \ref pom_load_string to load from a string.
+///
 /// On success, a configuration is returned and `*error` is set to `NULL`
 /// if `error` is not `NULL`.
 ///
@@ -99,11 +104,6 @@ typedef struct pom_item {
 /// there isn’t even enough memory for an out-of-memory
 /// error, `NULL` is returned and `*error` is set to `NULL`.
 ///
-/// Most of the time, you won't need this function:
-/// use \ref pom_load_file to load from a `FILE *`,
-/// \ref pom_load_path to load from a path,
-/// and \ref pom_load_string to load from a string.
-///
 /// `read_func` will be passed the `userdata` pointer passed to this function,
 /// a buffer, and the length of that buffer (which will be nonzero).
 /// It must fill out the buffer as much as possible,
@@ -121,7 +121,7 @@ pom_load(const char *filename,
 POM__MUST_USE_R;
 
 #ifndef POM_NO_STDIO
-/// Load configuration from a `FILE *`, which should be opened in binary mode.
+/// Load configuration from a `FILE *` opened in read-binary mode.
 ///
 /// On success, a configuration is returned and `*error` is set to `NULL`
 /// if `error` is not `NULL`.
@@ -187,7 +187,11 @@ pom_error_file(const pom_error *error);
 uint64_t
 pom_error_line(const pom_error *error);
 
-/// Get next error in error list.
+/// Get next error in error list, or `NULL` if this is the last error.
+///
+/// You can only call \ref pom_error_message, \ref pom_error_file, and \ref pom_error_line
+/// on the returned error, not \ref pom_error_print or \ref pom_error_to_string.
+/// (This is enforced with `const`-ness.)
 const pom_error *
 pom_error_next(const pom_error *error);
 
@@ -196,14 +200,14 @@ pom_error_next(const pom_error *error);
 ///
 /// Includes every error in an error list (see \ref pom_error_next).
 void
-pom_error_print(const pom_error *error);
+pom_error_print(pom_error *error);
 #endif
 
-/// Convert error to string. Return value must be `free()`d.
+/// Convert error to string. Return value is valid until `error` is `free()`’d.
 ///
 /// Includes every error in an error list (see \ref pom_error_next).
 POM__MUST_USE_L
-char *
+const char *
 pom_error_to_string(pom_error *error)
 POM__MUST_USE_R;