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241 lines
7.1 KiB
241 lines
7.1 KiB
From 4b5e9e71fbad66aef1db079905cba2db032a7515 Mon Sep 17 00:00:00 2001
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From: Phil Sutter <phil@nwl.cc>
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Date: Fri, 18 Sep 2020 18:48:14 +0200
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Subject: [PATCH] libxtables: Simplify pending extension registration
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Assuming that pending extensions are sorted by first name and family,
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then descending revision, the decision where to insert a newly
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registered extension may be simplified by memorizing the previous
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registration (which obviously is of same name and family and higher
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revision).
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As a side-effect, fix for unsupported old extension revisions lingering
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in pending extension list forever and being retried with every use of
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the given extension. Any revision being rejected by the kernel may
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safely be dropped iff a previous (read: higher) revision was accepted
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already.
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Yet another side-effect of this change is the removal of an unwanted
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recursion by xtables_fully_register_pending_*() into itself via
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xtables_find_*().
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Signed-off-by: Phil Sutter <phil@nwl.cc>
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(cherry picked from commit a1eaaceb0460b338294e40bdd5bc5186320a478c)
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---
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libxtables/xtables.c | 128 +++++++++++--------------------------------
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1 file changed, 33 insertions(+), 95 deletions(-)
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diff --git a/libxtables/xtables.c b/libxtables/xtables.c
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index de52e3e2bbc15..10d4e70328500 100644
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--- a/libxtables/xtables.c
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+++ b/libxtables/xtables.c
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@@ -203,8 +203,10 @@ struct xtables_match *xtables_matches;
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struct xtables_target *xtables_targets;
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/* Fully register a match/target which was previously partially registered. */
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-static bool xtables_fully_register_pending_match(struct xtables_match *me);
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-static bool xtables_fully_register_pending_target(struct xtables_target *me);
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+static bool xtables_fully_register_pending_match(struct xtables_match *me,
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+ struct xtables_match *prev);
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+static bool xtables_fully_register_pending_target(struct xtables_target *me,
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+ struct xtables_target *prev);
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#ifndef NO_SHARED_LIBS
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/* registry for loaded shared objects to close later */
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@@ -662,6 +664,7 @@ struct xtables_match *
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xtables_find_match(const char *name, enum xtables_tryload tryload,
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struct xtables_rule_match **matches)
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{
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+ struct xtables_match *prev = NULL;
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struct xtables_match **dptr;
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struct xtables_match *ptr;
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const char *icmp6 = "icmp6";
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@@ -683,8 +686,12 @@ xtables_find_match(const char *name, enum xtables_tryload tryload,
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if (extension_cmp(name, (*dptr)->name, (*dptr)->family)) {
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ptr = *dptr;
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*dptr = (*dptr)->next;
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- if (xtables_fully_register_pending_match(ptr))
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+ if (xtables_fully_register_pending_match(ptr, prev)) {
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+ prev = ptr;
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continue;
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+ } else if (prev) {
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+ continue;
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+ }
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*dptr = ptr;
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}
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dptr = &((*dptr)->next);
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@@ -778,6 +785,7 @@ xtables_find_match_revision(const char *name, enum xtables_tryload tryload,
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struct xtables_target *
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xtables_find_target(const char *name, enum xtables_tryload tryload)
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{
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+ struct xtables_target *prev = NULL;
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struct xtables_target **dptr;
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struct xtables_target *ptr;
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@@ -794,8 +802,12 @@ xtables_find_target(const char *name, enum xtables_tryload tryload)
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if (extension_cmp(name, (*dptr)->name, (*dptr)->family)) {
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ptr = *dptr;
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*dptr = (*dptr)->next;
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- if (xtables_fully_register_pending_target(ptr))
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+ if (xtables_fully_register_pending_target(ptr, prev)) {
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+ prev = ptr;
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continue;
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+ } else if (prev) {
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+ continue;
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+ }
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*dptr = ptr;
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}
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dptr = &((*dptr)->next);
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@@ -1098,64 +1110,27 @@ static int xtables_target_prefer(const struct xtables_target *a,
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b->revision, b->family);
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}
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-static bool xtables_fully_register_pending_match(struct xtables_match *me)
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+static bool xtables_fully_register_pending_match(struct xtables_match *me,
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+ struct xtables_match *prev)
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{
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- struct xtables_match **i, *old, *pos = NULL;
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+ struct xtables_match **i;
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const char *rn;
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- int compare;
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/* See if new match can be used. */
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rn = (me->real_name != NULL) ? me->real_name : me->name;
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if (!compatible_match_revision(rn, me->revision))
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return false;
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- old = xtables_find_match(me->name, XTF_DURING_LOAD, NULL);
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- while (old) {
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- compare = xtables_match_prefer(old, me);
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- if (compare == 0) {
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- fprintf(stderr,
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- "%s: match `%s' already registered.\n",
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- xt_params->program_name, me->name);
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- exit(1);
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- }
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-
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- /* Now we have two (or more) options, check compatibility. */
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- rn = (old->real_name != NULL) ? old->real_name : old->name;
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- if (compare > 0) {
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- /* Kernel tells old isn't compatible anymore??? */
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- if (!compatible_match_revision(rn, old->revision)) {
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- /* Delete old one. */
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- for (i = &xtables_matches; *i != old;)
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- i = &(*i)->next;
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- *i = old->next;
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- }
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- pos = old;
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- old = old->next;
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- if (!old)
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- break;
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- if (!extension_cmp(me->name, old->name, old->family))
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- break;
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- continue;
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- }
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-
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- /* Found right old */
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- pos = old;
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- break;
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- }
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-
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- if (!pos) {
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+ if (!prev) {
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/* Append to list. */
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for (i = &xtables_matches; *i; i = &(*i)->next);
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- } else if (compare < 0) {
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- /* Prepend it */
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- for (i = &xtables_matches; *i != pos; i = &(*i)->next);
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- } else if (compare > 0) {
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+ } else {
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/* Append it */
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- i = &pos->next;
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- pos = pos->next;
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+ i = &prev->next;
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+ prev = prev->next;
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}
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- me->next = pos;
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+ me->next = prev;
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*i = me;
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me->m = NULL;
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@@ -1260,11 +1235,11 @@ void xtables_register_target(struct xtables_target *me)
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#endif
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}
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-static bool xtables_fully_register_pending_target(struct xtables_target *me)
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+static bool xtables_fully_register_pending_target(struct xtables_target *me,
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+ struct xtables_target *prev)
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{
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- struct xtables_target **i, *old, *pos = NULL;
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+ struct xtables_target **i;
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const char *rn;
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- int compare;
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if (strcmp(me->name, "standard") != 0) {
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/* See if new target can be used. */
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@@ -1273,54 +1248,17 @@ static bool xtables_fully_register_pending_target(struct xtables_target *me)
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return false;
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}
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- old = xtables_find_target(me->name, XTF_DURING_LOAD);
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- while (old) {
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- compare = xtables_target_prefer(old, me);
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- if (compare == 0) {
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- fprintf(stderr,
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- "%s: target `%s' already registered.\n",
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- xt_params->program_name, me->name);
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- exit(1);
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- }
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-
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- /* Now we have two (or more) options, check compatibility. */
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- rn = (old->real_name != NULL) ? old->real_name : old->name;
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- if (compare > 0) {
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- /* Kernel tells old isn't compatible anymore??? */
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- if (!compatible_target_revision(rn, old->revision)) {
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- /* Delete old one. */
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- for (i = &xtables_targets; *i != old;)
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- i = &(*i)->next;
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- *i = old->next;
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- }
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- pos = old;
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- old = old->next;
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- if (!old)
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- break;
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- if (!extension_cmp(me->name, old->name, old->family))
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- break;
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- continue;
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- }
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-
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- /* Found right old */
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- pos = old;
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- break;
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- }
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-
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- if (!pos) {
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+ if (!prev) {
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/* Prepend to list. */
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i = &xtables_targets;
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- pos = xtables_targets;
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- } else if (compare < 0) {
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- /* Prepend it */
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- for (i = &xtables_targets; *i != pos; i = &(*i)->next);
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- } else if (compare > 0) {
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+ prev = xtables_targets;
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+ } else {
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/* Append it */
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- i = &pos->next;
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- pos = pos->next;
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+ i = &prev->next;
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+ prev = prev->next;
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}
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- me->next = pos;
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+ me->next = prev;
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*i = me;
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me->t = NULL;
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--
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2.40.0
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