"GOT", but the "O" is a cute, smiling sun Index | Thread

From:
Omar Polo <op@omarpolo.com>
Subject:
Re: gotwebd: openat(2) and less params for scraping repo info
To:
Omar Polo <op@omarpolo.com>
Cc:
gameoftrees@openbsd.org
Date:
Tue, 22 Nov 2022 12:07:49 +0100

Download raw body.

On 2022/11/15 15:56:29 +0100, Omar Polo <op@omarpolo.com> wrote:
> On 2022/11/15 09:56:23 +0100, Omar Polo <op@omarpolo.com> wrote:
> > Here's a reiteration of the previous diff.  Since i was already using
> > openat(2) in gotweb_get_repo_{description,clone_url} i thought i could
> > avoid the FILE handling at all: all we need to do is seek a bit to see
> > how big the file is and read from it.  It also changes len to be off_t
> > since now it's using lseek instead of fseek.
> > 
> > There is also another small change bundled.
> > gotweb_get_repo_description and clone_url differs in how they handle
> > the "len == 0" case when reading the file.  One sets the return to "",
> > the other one leaves NULL.  I'm normalizing the behaviour to return
> > NULL in both functions.
> 
> clarified this point with Tracey, the intent is to never end up
> passing NULL to fcgi_printf but since we already fall back to "" if
> the description or the clone url is NULL I think it's fine.  Tested
> with both file absent and/or empty and gotwebd doesn't print "(null)".
> 
> On a second thought we could drop a few more lines and don't special
> casing empty files.  We would end up allocating one byte, read zero
> into it and return.  Don't know if it's preferable, I'm being seduced
> by having more - in the diff.

ping.  I've extracted one bit and sent as a separate mail.

-----------------------------------------------
commit b7c8ea3da1b8cca57cb1d6c726ed9b2590ee5ec6 (w)
from: Omar Polo <op@omarpolo.com>
date: Tue Nov 22 11:00:49 2022 UTC
 
 gotwebd: rework gotweb_get_repo_{description,cloneurl}
 
  - use openat(2) since we've already opened the containing dir
  - simplify reading the files
 
diff 39afa5819b25cb2a5a8411de6f16d1e5667bb2c7 b7c8ea3da1b8cca57cb1d6c726ed9b2590ee5ec6
commit - 39afa5819b25cb2a5a8411de6f16d1e5667bb2c7
commit + b7c8ea3da1b8cca57cb1d6c726ed9b2590ee5ec6
blob - 87aa73baf749f6c131882947826effd5278c6c05
blob + 94e9ec2701b4224f2034e525cf69de75b4a4f65b
--- gotwebd/gotweb.c
+++ gotwebd/gotweb.c
@@ -28,6 +28,7 @@
 #include <dirent.h>
 #include <errno.h>
 #include <event.h>
+#include <fcntl.h>
 #include <imsg.h>
 #include <sha1.h>
 #include <stdio.h>
@@ -93,9 +94,9 @@ static const struct got_error *gotweb_get_repo_descrip
 static const struct got_error *gotweb_load_got_path(struct request *c,
     struct repo_dir *);
 static const struct got_error *gotweb_get_repo_description(char **,
-    struct server *, char *);
+    struct server *, int);
 static const struct got_error *gotweb_get_clone_url(char **, struct server *,
-    char *);
+    int);
 static const struct got_error *gotweb_render_navs(struct request *);
 static const struct got_error *gotweb_render_blame(struct request *);
 static const struct got_error *gotweb_render_briefs(struct request *);
@@ -2438,7 +2439,7 @@ done:
 	}
 	t->repo = repo;
 	error = gotweb_get_repo_description(&repo_dir->description, srv,
-	    repo_dir->path);
+	    dirfd(dt));
 	if (error)
 		goto err;
 	error = got_get_repo_owner(&repo_dir->owner, c);
@@ -2447,7 +2448,7 @@ done:
 	error = got_get_repo_age(&repo_dir->age, c, NULL, TM_DIFF);
 	if (error)
 		goto err;
-	error = gotweb_get_clone_url(&repo_dir->url, srv, repo_dir->path);
+	error = gotweb_get_clone_url(&repo_dir->url, srv, dirfd(dt));
 err:
 	free(dir_test);
 	if (dt != NULL && closedir(dt) == EOF && error == NULL)
@@ -2480,119 +2481,94 @@ gotweb_get_repo_description(char **description, struct
 }
 
 static const struct got_error *
-gotweb_get_repo_description(char **description, struct server *srv, char *dir)
+gotweb_get_repo_description(char **description, struct server *srv, int dir)
 {
 	const struct got_error *error = NULL;
-	FILE *f = NULL;
-	char *d_file = NULL;
-	unsigned int len;
-	size_t n;
+	int fd = -1;
+	off_t len;
 
 	*description = NULL;
 	if (srv->show_repo_description == 0)
 		return NULL;
 
-	if (asprintf(&d_file, "%s/description", dir) == -1)
-		return got_error_from_errno("asprintf");
-
-	f = fopen(d_file, "r");
-	if (f == NULL) {
+	fd = openat(dir, "description", O_RDONLY);
+	if (fd == -1) {
 		if (errno != ENOENT && errno != EACCES)
-			error = got_error_from_errno2("fopen", d_file);
+			error = got_error_from_errno2("openat", "description");
 		goto done;
 	}
 
-	if (fseek(f, 0, SEEK_END) == -1) {
-		error = got_ferror(f, GOT_ERR_IO);
-		goto done;
-	}
-	len = ftell(f);
+	len = lseek(fd, 0, SEEK_END);
 	if (len == -1) {
-		error = got_ferror(f, GOT_ERR_IO);
+		error = got_error_from_errno("lseek");
 		goto done;
 	}
 
-	if (len == 0) {
-		*description = strdup("");
-		if (*description == NULL)
-			error = got_error_from_errno("strdup");
+	if (lseek(fd, 0, SEEK_SET) == -1) {
+		error = got_error_from_errno("fseek");
 		goto done;
 	}
 
-	if (fseek(f, 0, SEEK_SET) == -1) {
-		error = got_ferror(f, GOT_ERR_IO);
-		goto done;
-	}
+	if (len > SIZE_MAX - 1)
+		len = SIZE_MAX - 1;
+
 	*description = calloc(len + 1, sizeof(**description));
 	if (*description == NULL) {
 		error = got_error_from_errno("calloc");
 		goto done;
 	}
 
-	n = fread(*description, 1, len, f);
-	if (n == 0 && ferror(f))
-		error = got_ferror(f, GOT_ERR_IO);
+	if (read(fd, *description, len) == -1)
+		error = got_error_from_errno("read");
 done:
-	if (f != NULL && fclose(f) == EOF && error == NULL)
-		error = got_error_from_errno("fclose");
-	free(d_file);
+	if (fd != -1 && close(fd) == -1 && error == NULL)
+		error = got_error_from_errno("close");
 	return error;
 }
 
 static const struct got_error *
-gotweb_get_clone_url(char **url, struct server *srv, char *dir)
+gotweb_get_clone_url(char **url, struct server *srv, int dir)
 {
 	const struct got_error *error = NULL;
-	FILE *f;
-	char *d_file = NULL;
-	unsigned int len;
-	size_t n;
+	int fd = -1;
+	off_t len;
 
 	*url = NULL;
-
 	if (srv->show_repo_cloneurl == 0)
 		return NULL;
 
-	if (asprintf(&d_file, "%s/cloneurl", dir) == -1)
-		return got_error_from_errno("asprintf");
-
-	f = fopen(d_file, "r");
-	if (f == NULL) {
+	fd = openat(dir, "cloneurl", O_RDONLY);
+	if (fd == -1) {
 		if (errno != ENOENT && errno != EACCES)
-			error = got_error_from_errno2("fopen", d_file);
+			error = got_error_from_errno2("openat", "cloneurl");
 		goto done;
 	}
 
-	if (fseek(f, 0, SEEK_END) == -1) {
-		error = got_ferror(f, GOT_ERR_IO);
-		goto done;
-	}
-	len = ftell(f);
+	len = lseek(fd, 0, SEEK_END);
 	if (len == -1) {
-		error = got_ferror(f, GOT_ERR_IO);
+		error = got_error_from_errno("lseek");
 		goto done;
 	}
-	if (len == 0)
-		goto done;
 
-	if (fseek(f, 0, SEEK_SET) == -1) {
-		error = got_ferror(f, GOT_ERR_IO);
+	if (lseek(fd, 0, SEEK_SET) == -1) {
+		error = got_error_from_errno("lseek");
 		goto done;
 	}
 
+	if (len > SIZE_MAX - 1)
+		len = SIZE_MAX - 1;
+
 	*url = calloc(len + 1, sizeof(**url));
 	if (*url == NULL) {
 		error = got_error_from_errno("calloc");
 		goto done;
 	}
 
-	n = fread(*url, 1, len, f);
-	if (n == 0 && ferror(f))
-		error = got_ferror(f, GOT_ERR_IO);
+	if (read(fd, *url, len) == -1)
+		error = got_error_from_errno("read");
 done:
-	if (f != NULL && fclose(f) == EOF && error == NULL)
+	if (fd != -1 && close(fd) == -1 && error == NULL)
 		error = got_error_from_errno("fclose");
-	free(d_file);
 	return error;
 }