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From 5024f01fec5e6c8fd05ca5451176878084e3f18f Mon Sep 17 00:00:00 2001
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From: David Herrmann <dh.herrmann@gmail.com>
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Date: Wed, 17 Sep 2014 09:06:49 +0200
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Subject: [PATCH] sysctl: make --prefix allow all kinds of sysctl paths
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Currently, we save arguments passed as --prefix directly and compare them
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later to absolute sysctl file-system paths. That is, you are required to
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specify arguments to --prefix with leading /proc/sys/. This is kinda
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uselesss. Furthermore, we replace dots by slashes in the name, which makes
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it impossible to match on specific sysfs paths that have dots in their
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name (like netdev names). The intention of this argument is clear, but it
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never worked as expected.
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This patch modifies --prefix to accept any kind of sysctl paths. It
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supports paths prefixed with /proc/sys for compatibility (but drops the
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erroneous dot->slash conversion), but instead applies normalize_sysctl()
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which turns any name or path into a proper path. It then appends
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/proc/sys/ so we can properly use it in matches.
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Thanks to Jan Synacek <jsynacek@redhat.com> for catching this!
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Conflicts:
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	src/sysctl/sysctl.c
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(cherry picked from commit 0e1f579227b08832437a7ac2227c7e4007a89d23)
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Resolves: #1138591
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---
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 src/sysctl/sysctl.c | 40 +++++++++++++++++++++++++++++-----------
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 1 file changed, 29 insertions(+), 11 deletions(-)
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diff --git a/src/sysctl/sysctl.c b/src/sysctl/sysctl.c
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index a9d4d53..d6f48dd 100644
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--- a/src/sysctl/sysctl.c
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+++ b/src/sysctl/sysctl.c
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@@ -51,9 +51,23 @@ static const char conf_file_dirs[] =
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 static char *normalize_sysctl(char *s) {
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         char *n;
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-        for (n = s; *n; n++)
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+        n = strpbrk(s, "/.");
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+        /* If the first separator is a slash, the path is
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+         * assumed to be normalized and slashes remain slashes
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+         * and dots remains dots. */
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+        if (!n || *n == '/')
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+                return s;
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+
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+        /* Otherwise, dots become slashes and slashes become
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+         * dots. Fun. */
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+        while (n) {
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                 if (*n == '.')
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                         *n = '/';
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+                else
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+                        *n = '.';
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+
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+                n = strpbrk(n + 1, "/.");
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+        }
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         return s;
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 }
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@@ -205,7 +219,7 @@ static int help(void) {
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         printf("%s [OPTIONS...] [CONFIGURATION FILE...]\n\n"
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                "Applies kernel sysctl settings.\n\n"
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                "  -h --help             Show this help\n"
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-               "     --prefix=PATH      Only apply rules that apply to paths with the specified prefix\n",
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+               "     --prefix=PATH      Only apply rules with the specified prefix\n",
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                program_invocation_short_name);
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         return 0;
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@@ -238,18 +252,22 @@ static int parse_argv(int argc, char *argv[]) {
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                 case ARG_PREFIX: {
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                         char *p;
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-                        char **l;
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-                        for (p = optarg; *p; p++)
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-                                if (*p == '.')
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-                                        *p = '/';
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-
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-                        l = strv_append(arg_prefixes, optarg);
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-                        if (!l)
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+                        /* We used to require people to specify absolute paths
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+                         * in /proc/sys in the past. This is kinda useless, but
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+                         * we need to keep compatibility. We now support any
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+                         * sysctl name available. */
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+                        normalize_sysctl(optarg);
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+                        if (startswith(optarg, "/proc/sys"))
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+                                p = strdup(optarg);
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+                        else
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+                                p = strappend("/proc/sys/", optarg);
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+
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+                        if (!p)
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                                 return log_oom();
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-                        strv_free(arg_prefixes);
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-                        arg_prefixes = l;
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+                        if (strv_push(&arg_prefixes, p) < 0)
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+                                return log_oom();
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                         break;
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                 }