readahead: Add tool to analyze the contents of the pack file. v3.

This patch adds code to compile 'systemd-readahead-analyze' and install
it into $bindir.

Use this program to parse the contents of the readahead pack file, or
an arbitrary pack file and display which files are listed in it, and
how much of the files are requested to be readahead.

This code is not new - it's partially taken from sreadahead (formerly
maintained by Arjan van der Ven and me, and was originally written
by me), and adapted with the right bits to parse the systemd
readahead pack files, which are slightly different in format.

v2 adds a common READAHEAD_PACK_FILE_VERSION used in all the code
to provide a quick way to assure all these programs are always
synchronized. v3 fixes the integer math.

4 files changed, 145 insertions, 2 deletions

diff --git a/src/readahead/readahead-analyze.c b/src/readahead/readahead-analyze.c
new file mode 100644
index 0000000000..6ee355146a
--- /dev/null
+++ b/src/readahead/readahead-analyze.c
@@ -0,0 +1,141 @@
+/*-*- Mode: C; c-basic-offset: 8; indent-tabs-mode: nil -*-*/
+
+/***
+  This file is part of systemd.
+
+  Copyright 2012 Auke Kok <auke-jan.h.kok@intel.com>
+
+  systemd is free software; you can redistribute it and/or modify it
+  under the terms of the GNU Lesser General Public License as published by
+  the Free Software Foundation; either version 2.1 of the License, or
+  (at your option) any later version.
+
+  systemd is distributed in the hope that it will be useful, but
+  WITHOUT ANY WARRANTY; without even the implied warranty of
+  MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
+  Lesser General Public License for more details.
+
+  You should have received a copy of the GNU Lesser General Public License
+  along with systemd; If not, see <http://www.gnu.org/licenses/>.
+***/
+
+
+#include <stdio.h>
+#include <stdlib.h>
+#include <stdbool.h>
+#include <unistd.h>
+#include <inttypes.h>
+#include <linux/limits.h>
+#include <sys/types.h>
+#include <sys/stat.h>
+#include <string.h>
+
+#include "readahead-common.h"
+
+
+int main(int argc, char *argv[])
+{
+        char line[1024];
+        char path[PATH_MAX];
+        FILE *pack;
+        int a;
+        int missing = 0;
+        off_t size;
+        long tsize = 0;
+        uint64_t inode;
+        uint32_t b;
+        uint32_t c;
+        struct stat st;
+        int pagesize = getpagesize();
+
+        if (argc != 2)
+                snprintf(path, PATH_MAX, "/.readahead");
+        else
+                snprintf(path, PATH_MAX, "%s", argv[1]);
+
+        pack = fopen(path, "r");
+        if (!pack) {
+                fprintf(stderr, "Pack file missing\n");
+                exit(EXIT_FAILURE);
+        }
+
+        if (!(fgets(line, sizeof(line), pack))) {
+                fprintf(stderr, "Pack file corrupt\n");
+                exit(EXIT_FAILURE);
+        }
+
+        if (!strstr(line, READAHEAD_PACK_FILE_VERSION)) {
+                fprintf(stderr, "Pack file version incompatible with this parser\n");
+                exit(EXIT_FAILURE);
+        }
+
+        if ((a = getc(pack)) == EOF) {
+                fprintf(stderr, "Pack file corrupt\n");
+                exit(EXIT_FAILURE);
+        }
+
+        fprintf(stdout, "   pct  sections     size: path\n");
+        fprintf(stdout, "   ===  ========     ====: ====\n");
+
+        while(true) {
+                int pages = 0;
+                int sections = 0;
+
+                if (!fgets(path, sizeof(path), pack))
+                        break; /* done */
+
+                path[strlen(path)-1] = 0;
+
+                if (fread(&inode, sizeof(inode), 1, pack) != 1) {
+                        fprintf(stderr, "Pack file corrupt\n");
+                        exit(EXIT_FAILURE);
+                }
+
+                while (true) {
+                        if (fread(&b, sizeof(b), 1, pack) != 1  ||
+                            fread(&c, sizeof(c), 1, pack) != 1) {
+                                fprintf(stderr, "Pack file corrupt\n");
+                                exit(EXIT_FAILURE);
+                        }
+                        if ((b == 0) && (c == 0))
+                                break;
+
+                        /* Uncomment this to get all the chunks separately
+                        fprintf(stdout, " %d: %d %d\n", sections, b, c);
+                         */
+
+                        pages += (c - b);
+                        sections++;
+                }
+
+                if (stat(path, &st) == 0) {
+                        if (sections == 0)
+                                size = st.st_size;
+                        else
+                                size = pages * pagesize;
+
+                        tsize += size;
+
+                        fprintf(stdout, "  %4d%% (%2d) %12ld: %s\n",
+                                sections ? (int)(size / st.st_size * 100.0) : 100,
+                                sections ? sections : 1,
+                                (unsigned long)size,
+                                path);
+                } else {
+                        fprintf(stdout, "  %4dp (%2d) %12s: %s (MISSING)\n",
+                                sections ? pages : -1,
+                                sections ? sections : 1,
+                                "???",
+                                path);
+                        missing++;
+                }
+
+        }
+
+        fprintf(stdout, "\nHOST:    %s", line);
+        fprintf(stdout, "TYPE:    %c\n", a);
+        fprintf(stdout, "MISSING: %d\n", missing);
+        fprintf(stdout, "TOTAL:   %ld\n", tsize);
+
+        exit(EXIT_SUCCESS);
+}
diff --git a/src/readahead/readahead-collect.c b/src/readahead/readahead-collect.c
index 1d56b11065..c4bcd4e162 100644
--- a/src/readahead/readahead-collect.c
+++ b/src/readahead/readahead-collect.c
@@ -493,7 +493,7 @@ done:
                 goto finish;
         }
 
-        fputs(CANONICAL_HOST ";VERSION=2\n", pack);
+        fputs(CANONICAL_HOST READAHEAD_PACK_FILE_VERSION, pack);
         putc(on_ssd ? 'S' : 'R', pack);
 
         if (on_ssd || on_btrfs) {
diff --git a/src/readahead/readahead-common.h b/src/readahead/readahead-common.h
index 9962dd527a..3056a02485 100644
--- a/src/readahead/readahead-common.h
+++ b/src/readahead/readahead-common.h
@@ -29,6 +29,8 @@
 
 #define READAHEAD_FILE_SIZE_MAX (10*1024*1024)
 
+#define READAHEAD_PACK_FILE_VERSION ";VERSION=2\n"
+
 int file_verify(int fd, const char *fn, off_t file_size_max, struct stat *st);
 
 int fs_on_ssd(const char *p);
diff --git a/src/readahead/readahead-replay.c b/src/readahead/readahead-replay.c
index 344dcd4041..fc2c33fcc1 100644
--- a/src/readahead/readahead-replay.c
+++ b/src/readahead/readahead-replay.c
@@ -183,7 +183,7 @@ static int replay(const char *root) {
 
         char_array_0(line);
 
-        if (!streq(line, CANONICAL_HOST ";VERSION=2\n")) {
+        if (!streq(line, CANONICAL_HOST READAHEAD_PACK_FILE_VERSION)) {
                 log_debug("Pack file host or version type mismatch.");
                 goto finish;
         }