Re: Value size limits on git config files

[Erik Faye-Lund <kusmabite@gmail.com>]

On Tue, Apr 5, 2011 at 6:29 PM, Jeff Adamson <jwa@urbancode.com> wrote:
> When trying to incorporate large aliases into my ~/.gitconfig file via
> `git config --global "!$(cat myscript)"`, I determined that there
> appears to be a limit to the size of a value.  When exceeded, git
> prints out "fatal: bad config file line 82 in ~/.gitconfig".  I was
> able to strip enough comments and such from myscript that it then no
> longer invalidated the config once the value was less than 1024 chars.
>  (Minor aside, I am doing this as a small experiment to potentially
> aid in synchronizing all my git behaviors across machines by inlining
> them into the config file.  Whether this is a good path to explore or
> not is a separate issue.)
>
> My questions are:
>    Is this 1024 char limit on config file values documented somewhere?
>    Should it be considered a bug that git config can write out config
> files which it can not then read (e.g. it should be changed to either
> enforce the value-length limit during writing, or the parser updated
> to handle large values)?
>

It's due to use of a fixed-size buffer. This patch fixes it for me:

diff --git a/config.c b/config.c
index 0abcada..bc6ea49 100644
--- a/config.c
+++ b/config.c
@@ -133,23 +133,20 @@ static int get_next_char(void)

 static char *parse_value(void)
 {
-	static char value[1024];
-	int quote = 0, comment = 0, len = 0, space = 0;
+	struct strbuf value = STRBUF_INIT;
+	int quote = 0, comment = 0, space = 0;

 	for (;;) {
 		int c = get_next_char();
-		if (len >= sizeof(value) - 1)
-			return NULL;
 		if (c == '\n') {
 			if (quote)
 				return NULL;
-			value[len] = 0;
-			return value;
+			return strbuf_detach(&value, NULL);
 		}
 		if (comment)
 			continue;
 		if (isspace(c) && !quote) {
-			if (len)
+			if (value.len)
 				space++;
 			continue;
 		}
@@ -160,7 +157,7 @@ static char *parse_value(void)
 			}
 		}
 		for (; space; space--)
-			value[len++] = ' ';
+			strbuf_addch(&value, ' ');
 		if (c == '\\') {
 			c = get_next_char();
 			switch (c) {
@@ -180,16 +177,17 @@ static char *parse_value(void)
 				break;
 			/* Reject unknown escape sequences */
 			default:
+				strbuf_release(&value);
 				return NULL;
 			}
-			value[len++] = c;
+			strbuf_addch(&value, c);
 			continue;
 		}
 		if (c == '"') {
 			quote = 1-quote;
 			continue;
 		}
-		value[len++] = c;
+		strbuf_addch(&value, c);
 	}
 }

@@ -200,7 +198,7 @@ static inline int iskeychar(int c)

 static int get_value(config_fn_t fn, void *data, char *name, unsigned int len)
 {
-	int c;
+	int c, ret;
 	char *value;

 	/* Get the full name */
@@ -226,7 +224,9 @@ static int get_value(config_fn_t fn, void *data,
char *name, unsigned int len)
 		if (!value)
 			return -1;
 	}
-	return fn(name, value, data);
+	ret = fn(name, value, data);
+	free(value);
+	return ret;
 }

 static int get_extended_base_var(char *name, int baselen, int c)