Calculate the size of the backing store file.

A size can be specified in absolute terms (suffix: k, m, g, t supported),
but also as a percentage of the filesystems free space (suffix '%').

If the specified size is larger than an off_t can cope, we bisect 
repeatedly until it can.

If the size exceeds the available space of the filesystem, we truncate
to 80% of the free space.

Then round down to an integral number of blocks, sized by the larger
of the filesystem blocksize and the pagesize.

This was tricker than I'd expected...



git-svn-id: http://www.varnish-cache.org/svn/trunk@175 d4fa192b-c00b-0410-8231-f00ffab90ce4

bin/varnishd/storage_file.c

@@ -5,17 +5,222 @@
  */
 
 #include <assert.h>
+#include <stdio.h>
+#include <unistd.h>
+#include <fcntl.h>
+#include <errno.h>
+#include <stdint.h>
+#include <limits.h>
 #include <stdlib.h>
+#include <string.h>
 #include <sys/queue.h>
+#include <sys/stat.h>
 #include <pthread.h>
+#include <sys/param.h>
+#include <sys/mount.h>
 
 #include "vcl_lang.h"
+#include "libvarnish.h"
 #include "cache.h"
 
+struct smf_sc {
+	char			*filename;
+	int			fd;
+	uintmax_t		filesize;
+};
+
 struct smf {
 	struct storage		s;
 };
 
+/*--------------------------------------------------------------------*/
+
+static void
+smf_calcsize(struct smf_sc *sc, const char *size, int newfile)
+{
+	uintmax_t l;
+	unsigned bs;
+	char suff[2];
+	int i;
+	off_t o;
+	struct statfs fsst;
+	struct stat st;
+
+	AZ(fstat(sc->fd, &st));
+	AZ(fstatfs(sc->fd, &fsst));
+
+	/* We use units of the larger of filesystem blocksize and pagesize */
+	bs = getpagesize();
+	if (bs < fsst.f_bsize)
+		bs = fsst.f_bsize;
+
+	assert(S_ISREG(st.st_mode));
+
+	i = sscanf(size, "%ju%1s", &l, suff); /* can return -1, 0, 1 or 2 */
+
+	if (i == 0) {
+		fprintf(stderr,
+		    "Error: (-sfile) size \"%s\" not understood\n", size);
+		exit (2);
+	}
+
+	if (i >= 1 && l == 0) {
+		fprintf(stderr,
+		    "Error: (-sfile) zero size not permitted\n");
+		exit (2);
+	}
+
+	if (i == -1 && !newfile) /* Use the existing size of the file */
+		l = st.st_size;
+
+	/* We must have at least one block */
+	if (l < bs) {	
+		if (i == -1) {
+			fprintf(stderr,
+			    "Info: (-sfile) default to 80%% size\n");
+			l = 80;
+			suff[0] = '%';
+			i = 2;
+		}
+
+		if (i == 2) {
+			if (suff[0] == 'k' || suff[0] == 'K')
+				l *= 1024UL;
+			else if (suff[0] == 'm' || suff[0] == 'M')
+				l *= 1024UL * 1024UL;
+			else if (suff[0] == 'g' || suff[0] == 'G')
+				l *= 1024UL * 1024UL * 1024UL;
+			else if (suff[0] == 't' || suff[0] == 'T')
+				l *= (uintmax_t)(1024UL * 1024UL) *
+				    (uintmax_t)(1024UL * 1024UL);
+			else if (suff[0] == '%') {
+				l *= fsst.f_bsize * fsst.f_bavail;
+				l /= 100;
+			}
+		}
+
+		o = l;
+		if (o != l || o < 0) {
+			fprintf(stderr,
+			    "Warning: size reduced to system limit (off_t)\n");
+			do {
+				l >>= 1;
+				o = l;
+			} while (o != l || o < 0);
+		}
+
+		if (l < st.st_size) {
+			AZ(ftruncate(sc->fd, l));
+		} else if (l - st.st_size > fsst.f_bsize * fsst.f_bavail) {
+			fprintf(stderr,
+			    "Warning: size larger than filesystem free space,"
+			    " reduced to 80%% of free space.\n");
+			l = (fsst.f_bsize * fsst.f_bavail * 80) / 100;
+		}
+	}
+
+	/* round down to of filesystem blocksize or pagesize */
+	l -= (l % bs);
+
+	assert(l >= bs);
+
+	printf("file %s size %ju bytes (%ju fs-blocks, %ju pages)\n",
+	    sc->filename, l, l / fsst.f_bsize, l / getpagesize());
+
+	sc->filesize = l;
+}
+
+static void
+smf_initfile(struct smf_sc *sc, const char *size, int newfile)
+{
+	smf_calcsize(sc, size, newfile);
+}
+
+static void
+smf_init(struct stevedore *parent, const char *spec)
+{
+	char *size;
+	char *p, *q;
+	struct stat st;
+	struct smf_sc *sc;
+
+	sc = calloc(sizeof *sc, 1);
+	assert(sc != NULL);
+
+	/* If no size specified, use 50% of filesystem free space */
+	if (spec == NULL || *spec == '\0')
+		spec = "/tmp,50%";
+
+	if (strchr(spec, ',') == NULL)
+		asprintf(&p, "%s,", spec);
+	else
+		p = strdup(spec);
+	assert(p != NULL);
+	size = strchr(p, ',');
+	assert(size != NULL);
+
+	*size++ = '\0';
+
+	/* try to create a new file of this name */
+	sc->fd = open(p, O_RDWR | O_CREAT | O_EXCL, 0600);
+	if (sc->fd >= 0) {
+		sc->filename = p;
+		smf_initfile(sc, size, 1);
+		return;
+	}
+
+	/* it must exist then */
+	if (stat(p, &st)) {
+		fprintf(stderr,
+		    "Error: (-sfile) \"%s\" "
+		    "does not exist and could not be created\n", p);
+		exit (2);
+	}
+
+	/* and it should be a file or directory */
+	if (!(S_ISREG(st.st_mode) || S_ISDIR(st.st_mode))) {
+		fprintf(stderr,
+		    "Error: (-sfile) \"%s\" "
+		    "is neither file nor directory\n", p);
+		exit (2);
+	}
+
+	if (S_ISREG(st.st_mode)) {
+		sc->fd = open(p, O_RDWR);
+		if (sc->fd < 0) {
+			fprintf(stderr,
+			    "Error: (-sfile) \"%s\" "
+			    "could not open (%s)\n", p, strerror(errno));
+			exit (2);
+		}
+		AZ(fstat(sc->fd, &st));
+		if (!S_ISREG(st.st_mode)) {
+			fprintf(stderr,
+			    "Error: (-sfile) \"%s\" "
+			    "was not a file after opening\n", p);
+			exit (2);
+		}
+		sc->filename = p;
+		smf_initfile(sc, size, 0);
+		return;
+	}
+
+	asprintf(&q, "%s/varnish.XXXXXX", p);
+	assert(q != NULL);
+	sc->fd = mkstemp(q);
+	if (sc->fd < 0) {
+		fprintf(stderr,
+		    "Error: (-sfile) \"%s\" "
+		    "mkstemp(%s) failed (%s)\n", p, q, strerror(errno));
+		exit (2);
+	}
+	AZ(unlink(q));
+	asprintf(&sc->filename, "%s (unlinked)", q);
+	assert(sc->filename != NULL);
+	free(q);
+	smf_initfile(sc, size, 1);
+}
+
 static struct storage *
 smf_alloc(struct stevedore *st __unused, unsigned size)
 {
@@ -42,7 +247,7 @@ smf_free(struct storage *s)
 
 struct stevedore smf_stevedore = {
 	"file",
-	NULL,			/* init */
+	smf_init,		/* init */
 	NULL,			/* open */
 	smf_alloc,
 	smf_free