From c67972e3c5b9c665b15bca3491e2f46cf478a7bd Mon Sep 17 00:00:00 2001
From: schneider <schneider@blinkenlichts.net>
Date: Fri, 3 Apr 2020 18:27:10 +0200
Subject: [PATCH] refact(config): Make config parser more robust
Introduces a small state machine which parses the file character by
character. This eases the logic around parsing whole lines
significantly.
Now also trims lines, handling all non printable characters correctly.
---
epicardium/modules/config.c | 160 +++++++++++++++---------------------
1 file changed, 64 insertions(+), 96 deletions(-)
diff --git a/epicardium/modules/config.c b/epicardium/modules/config.c
index 7371f02a9..8e39efd2c 100644
--- a/epicardium/modules/config.c
+++ b/epicardium/modules/config.c
@@ -125,25 +125,37 @@ static void add_config_pair(
slot->value_offset = value_offset;
}
+static char *trim(char *str)
+{
+ char *start = str;
+ while (*start && !isgraph((int)*start))
+ start++;
+
+ if (strlen(start) > 0) {
+ char *end = start + strlen(start) - 1;
+ while (*end && !isgraph((int)*end))
+ end--;
+ end[1] = 0;
+ }
+ return start;
+}
+
// parses one line of the config file
-static void
-parse_line(char *line, char *eol, int line_number, size_t line_offset)
+static void parse_line(char *line, int line_number, size_t line_offset)
{
char *line_start = line;
- //skip leading whitespace
- while (*line && isspace((int)*line))
- ++line;
+ line = trim(line);
- char *key = line;
- if (*key == '#') {
+ //printf(line);
+ if (*line == '#') {
//skip comments
return;
}
char *eq = strchr(line, '=');
if (!eq) {
- if (*key) {
+ if (*line) {
LOG_WARN(
"card10.cfg",
"line %d: syntax error",
@@ -152,26 +164,15 @@ parse_line(char *line, char *eol, int line_number, size_t line_offset)
}
return;
}
+ *eq = 0;
- char *e_key = eq - 1;
- //skip trailing whitespace in key
- while (e_key > key && isspace((int)*e_key))
- --e_key;
- e_key[1] = '\0';
+ char *key = trim(line);
if (*key == '\0') {
LOG_WARN("card10.cfg", "line %d: empty key", line_number);
return;
}
- char *value = eq + 1;
- //skip leading whitespace
- while (*value && isspace((int)*value))
- ++value;
-
- char *e_val = eol - 1;
- //skip trailing whitespace
- while (e_val > value && isspace((int)*e_val))
- --e_val;
+ char *value = trim(eq + 1);
if (*value == '\0') {
LOG_WARN(
"card10.cfg",
@@ -187,16 +188,39 @@ parse_line(char *line, char *eol, int line_number, size_t line_offset)
add_config_pair(key, value, line_number, value_offset);
}
-// convert windows line endings to unix line endings.
-// we don't care about the extra empty lines
-static void convert_crlf_to_lflf(char *buf, int n)
+typedef struct {
+ int line_number;
+ int file_offset;
+ int line_start;
+ char line[MAX_LINE_LENGTH + 1];
+ int line_length;
+} parser_state;
+
+int parse_character(char c, parser_state *s)
{
- while (n--) {
- if (*buf == '\r') {
- *buf = '\n';
+ if (c != '\r' && c != '\n') {
+ if (s->line_length == MAX_LINE_LENGTH) {
+ LOG_WARN(
+ "card10.cfg",
+ "line:%d: too long - aborting",
+ s->line_number
+ );
+ return -1;
+ }
+ s->line[s->line_length++] = c;
+ } else {
+ s->line[s->line_length] = 0;
+ //printf("New line: %s (%d %d)\n", s->line, s->line_number, s->line_start);
+ parse_line(s->line, s->line_number, s->line_start);
+ s->line_length = 0;
+ s->line_start = s->file_offset + 1;
+ if (c == '\n') {
+ s->line_number++;
}
- buf++;
}
+
+ s->file_offset++;
+ return 0;
}
// parses the entire config file
@@ -213,77 +237,21 @@ void load_config(void)
);
return;
}
- char buf[MAX_LINE_LENGTH + 1];
- int line_number = 0;
- size_t file_offset = 0;
+
+ char buf[128];
int nread;
+ parser_state s;
+ memset(&s, 0, sizeof(s));
+ s.line_number = 1;
do {
- nread = epic_file_read(fd, buf, MAX_LINE_LENGTH);
- convert_crlf_to_lflf(buf, nread);
- if (nread < MAX_LINE_LENGTH) {
- //add fake EOL to ensure termination
- buf[nread++] = '\n';
+ nread = epic_file_read(fd, buf, sizeof(buf));
+ int i;
+ for (i = 0; i < nread; i++) {
+ parse_character(buf[i], &s);
}
- //zero-terminate buffer
- buf[nread] = '\0';
- char *line = buf;
- char *eol = NULL;
- int last_eol = 0;
- while (line) {
- //line points one character past the last (if any) '\n' hence '- 1'
- last_eol = line - buf - 1;
- eol = strchr(line, '\n');
- ++line_number;
- if (eol) {
- *eol = '\0';
- parse_line(line, eol, line_number, file_offset);
- file_offset += eol - line + 1;
- line = eol + 1;
- continue;
- }
- if (line == buf) {
- //line did not fit into buf
- LOG_WARN(
- "card10.cfg",
- "line:%d: too long - aborting",
- line_number
- );
- return;
- }
- int seek_back = last_eol - nread;
+ } while (nread == sizeof(buf));
+ parse_character('\n', &s);
- LOG_DEBUG(
- "card10.cfg",
- "nread, last_eol, seek_back: %d,%d,%d",
- nread,
- last_eol,
- seek_back
- );
- assert(seek_back <= 0);
- if (!seek_back) {
- break;
- }
-
- int rc = epic_file_seek(fd, seek_back, SEEK_CUR);
- if (rc < 0) {
- LOG_ERR("card10.cfg", "seek failed, aborting");
- return;
- }
- char newline;
- rc = epic_file_read(fd, &newline, 1);
- if (rc < 0 || (newline != '\n' && newline != '\r')) {
- LOG_ERR("card10.cfg", "read failed, aborting");
- LOG_DEBUG(
- "card10.cfg",
- "read failed at read-back of newline: rc: %d read: %d",
- rc,
- (int)newline
- );
- return;
- }
- break;
- }
- } while (nread == MAX_LINE_LENGTH);
epic_file_close(fd);
}
--
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