saait

commit c8d25c5c048770baa20b974084a77da70d130ffc
parent 7c19117912a82008cd2e65a62c399ec7f6c439ab
Author: Hiltjo Posthuma <hiltjo@codemadness.org>
Date:   Sun,  4 Dec 2016 13:48:53 +0100

improve readfile(): reduce memory usage, optimize for small files, remove extra copy (memcpy).

Diffstat:
M
TODO
 | 
25
+++++++------------------
M
saait.c
 | 
20
++++++++++----------

2 files changed, 17 insertions(+), 28 deletions(-)
diff --git a/TODO b/TODO
@@ -1,19 +1,11 @@
-optimize readfile: don't copy data twice (memcpy).
-
-reduce memory usage.
-
-allow to override output filename (for no prefix number).
-
-writepage() improve error messages for filenames (error on line ...).
+x optimize readfile: don't copy data twice (memcpy).
+x reduce memory usage.
+x allow to override output filename (for no prefix number).
+- writepage() improve error messages for filenames (error on line ...).
 	show template name and filename.
-
-cfgfile: spaces around = skip
-
-don't use strndup or wrap it.
-
-simplify date parsing.
-
-improve documentation
+- cfgfile: spaces around = skip
+x don't use strndup or wrap it.
+- improve documentation
 
 make template structure:
 
@@ -21,17 +13,14 @@ make template structure:
 	templates/name/item.ext
 	templates/name/footer.ext
 
-
 add able to check unused variables (-w option?).
 	add used counter to variable struct.
 
-
 must work on: Linux, OpenBSD, MingW (Windows).
 	glibc
 	musl
 	OpenBSD libc
 
-
 - show line number in error
 	improve
 - about 500 LOC
diff --git a/saait.c b/saait.c
@@ -106,24 +106,24 @@ char *
 readfile(const char *file)
 {
 	FILE *fp;
-	char buf[BUFSIZ], *s = NULL;
+	char *buf = NULL;
 	size_t n, len = 0, size = 0;
 
 	fp = efopen(file, "rb");
-	s = ecalloc(1, size + 1);
+	buf = ecalloc(1, size + 1); /* always allocate an empty buffer */
 	while (!feof(fp)) {
-		if (!(n = fread(buf, 1, sizeof(buf), fp)))
-			break;
-		if (len + n > size) {
-			size = size ? size * 2 : sizeof(buf); /* greedy allocation */
-			if (!(s = realloc(s, size + 1))) {
+		if (len + BUFSIZ + 1 > size) {
+			/* non-greedy allocation (common case is small textfiles) */
+			size += BUFSIZ;
+			if (!(buf = realloc(buf, size + 1))) {
 				fprintf(stderr, "realloc: %s\n", strerror(errno));
 				exit(1);
 			}
 		}
-		memcpy(&s[len], buf, n);
+		if (!(n = fread(&buf[len], 1, BUFSIZ, fp)))
+			break;
 		len += n;
-		s[len] = '\0';
+		buf[len] = '\0';
 	}
 	if (ferror(fp)) {
 		fprintf(stderr, "fread: file: %s %s\n", file, strerror(errno));
@@ -131,7 +131,7 @@ readfile(const char *file)
 	}
 	fclose(fp);
 
-	return s;
+	return buf;
 }
 
 struct variable *