Use strbuf for reading configuration files

Use struct strbuf from Git instead of fixed-size buffers to remove the
limit on the length of configuration file lines and refactor
read_config_line() to improve readability.

Note that this also fixes a buffer overflow that existed with the
original fixed-size buffer implementation.

Signed-off-by: Lukas Fleischer <cgit@cryptocrack.de>

1 files changed, 33 insertions, 31 deletions

diff --git a/configfile.c b/configfile.c
index d98989c..31fe5c8 100644
--- a/configfile.c
+++ b/configfile.c
@@ -31,45 +31,45 @@ static void skip_line(FILE *f)
                 ;
 }
 
-static int read_config_line(FILE *f, char *line, const char **value, int bufsize)
+static int read_config_line(FILE *f, struct strbuf *name, struct strbuf *value)
 {
-        int i = 0, isname = 0;
+        int c = next_char(f);
 
-        *value = NULL;
-        while (i < bufsize - 1) {
-                int c = next_char(f);
-                if (!isname && (c == '#' || c == ';')) {
-                        skip_line(f);
-                        continue;
-                }
-                if (!isname && isspace(c))
-                        continue;
+        strbuf_reset(name);
+        strbuf_reset(value);
 
-                if (c == '=' && !*value) {
-                        line[i] = 0;
-                        *value = &line[i + 1];
-                } else if (c == '\n' && !isname) {
-                        i = 0;
-                        continue;
-                } else if (c == '\n' || c == EOF) {
-                        line[i] = 0;
+        /* Skip comments and preceding spaces. */
+        for(;;) {
+                if (c == '#' || c == ';')
+                        skip_line(f);
+                else if (!isspace(c))
                         break;
-                } else {
-                        line[i] = c;
-                }
-                isname = 1;
-                i++;
+                c = next_char(f);
         }
-        line[i + 1] = 0;
-        return i;
+
+        /* Read variable name. */
+        while (c != '=') {
+                if (c == '\n' || c == EOF)
+                        return 0;
+                strbuf_addch(name, c);
+                c = next_char(f);
+        }
+
+        /* Read variable value. */
+        c = next_char(f);
+        while (c != '\n' && c != EOF) {
+                strbuf_addch(value, c);
+                c = next_char(f);
+        }
+
+        return 1;
 }
 
 int parse_configfile(const char *filename, configfile_value_fn fn)
 {
         static int nesting;
-        int len;
-        char line[256];
-        const char *value;
+        struct strbuf name = STRBUF_INIT;
+        struct strbuf value = STRBUF_INIT;
         FILE *f;
 
         /* cancel deeply nested include-commands */
@@ -78,10 +78,12 @@ int parse_configfile(const char *filename, configfile_value_fn fn)
         if (!(f = fopen(filename, "r")))
                 return -1;
         nesting++;
-        while ((len = read_config_line(f, line, &value, sizeof(line))) > 0)
-                fn(line, value);
+        while (read_config_line(f, &name, &value))
+                fn(name.buf, value.buf);
         nesting--;
         fclose(f);
+        strbuf_release(&name);
+        strbuf_release(&value);
         return 0;
 }