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glibc/SOURCES/glibc-rh1817513-117.patch

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commit 73b6e50a22dea9ae6144beaaa675d2ac62c281ca
Author: Florian Weimer <fweimer@redhat.com>
Date: Fri Dec 4 09:13:43 2020 +0100
elf: Implement tail merging of strings in ldconfig
This simplifies the string table construction in elf/cache.c
because there is no more need to keep track of offsets explicitly;
the string table implementation does this internally.
This change slightly reduces the size of the cache on disk. The
file format does not change as a result. The strings are
null-terminated, without explicit length, so tail merging is
transparent to readers.
Reviewed-by: Adhemerval Zanella <adhemerval.zanella@linaro.org>
diff --git a/elf/Makefile b/elf/Makefile
index abb3e9d1179ef5cd..a3e802a9a99b759c 100644
--- a/elf/Makefile
+++ b/elf/Makefile
@@ -112,7 +112,8 @@ others-static += ldconfig
others += ldconfig
install-rootsbin += ldconfig
-ldconfig-modules := cache readlib xmalloc xstrdup chroot_canon static-stubs
+ldconfig-modules := cache readlib xmalloc xstrdup chroot_canon static-stubs \
+ stringtable
extra-objs += $(ldconfig-modules:=.o)
others-extras = $(ldconfig-modules)
endif
diff --git a/elf/cache.c b/elf/cache.c
index 5a8f1ad70cc3fead..f773cacacf26db1c 100644
--- a/elf/cache.c
+++ b/elf/cache.c
@@ -35,11 +35,15 @@
#include <ldconfig.h>
#include <dl-cache.h>
#include <version.h>
+#include <stringtable.h>
+
+/* Used to store library names, paths, and other strings. */
+static struct stringtable strings;
struct cache_entry
{
- char *lib; /* Library name. */
- char *path; /* Path to find library. */
+ struct stringtable_entry *lib; /* Library name. */
+ struct stringtable_entry *path; /* Path to find library. */
int flags; /* Flags to indicate kind of library. */
unsigned int osversion; /* Required OS version. */
uint64_t hwcap; /* Important hardware capabilities. */
@@ -300,7 +304,7 @@ static int
compare (const struct cache_entry *e1, const struct cache_entry *e2)
{
/* We need to swap entries here to get the correct sort order. */
- int res = _dl_cache_libcmp (e2->lib, e1->lib);
+ int res = _dl_cache_libcmp (e2->lib->string, e1->lib->string);
if (res == 0)
{
if (e1->flags < e2->flags)
@@ -369,26 +373,24 @@ save_cache (const char *cache_name)
{
/* The cache entries are sorted already, save them in this order. */
- /* Count the length of all strings. */
- /* The old format doesn't contain hwcap entries and doesn't contain
- libraries in subdirectories with hwcaps entries. Count therefore
- also all entries with hwcap == 0. */
- size_t total_strlen = 0;
struct cache_entry *entry;
/* Number of cache entries. */
int cache_entry_count = 0;
- /* Number of normal cache entries. */
+ /* The old format doesn't contain hwcap entries and doesn't contain
+ libraries in subdirectories with hwcaps entries. Count therefore
+ also all entries with hwcap == 0. */
int cache_entry_old_count = 0;
for (entry = entries; entry != NULL; entry = entry->next)
{
- /* Account the final NULs. */
- total_strlen += strlen (entry->lib) + strlen (entry->path) + 2;
++cache_entry_count;
if (entry->hwcap == 0)
++cache_entry_old_count;
}
+ struct stringtable_finalized strings_finalized;
+ stringtable_finalize (&strings, &strings_finalized);
+
/* Create the on disk cache structure. */
struct cache_file *file_entries = NULL;
size_t file_entries_size = 0;
@@ -432,7 +434,7 @@ save_cache (const char *cache_name)
sizeof CACHE_VERSION - 1);
file_entries_new->nlibs = cache_entry_count;
- file_entries_new->len_strings = total_strlen;
+ file_entries_new->len_strings = strings_finalized.size;
file_entries_new->flags = cache_file_new_flags_endian_current;
}
@@ -449,20 +451,20 @@ save_cache (const char *cache_name)
str_offset = 0;
/* An array for all strings. */
- char *strings = xmalloc (total_strlen);
- char *str = strings;
int idx_old;
int idx_new;
for (idx_old = 0, idx_new = 0, entry = entries; entry != NULL;
entry = entry->next, ++idx_new)
{
- /* First the library. */
if (opt_format != opt_format_new && entry->hwcap == 0)
{
file_entries->libs[idx_old].flags = entry->flags;
/* XXX: Actually we can optimize here and remove duplicates. */
file_entries->libs[idx_old].key = str_offset + pad;
+ file_entries->libs[idx_new].key = str_offset + entry->lib->offset;
+ file_entries->libs[idx_new].value
+ = str_offset + entry->path->offset;
}
if (opt_format != opt_format_old)
{
@@ -473,20 +475,12 @@ save_cache (const char *cache_name)
file_entries_new->libs[idx_new].flags = entry->flags;
file_entries_new->libs[idx_new].osversion = entry->osversion;
file_entries_new->libs[idx_new].hwcap = entry->hwcap;
- file_entries_new->libs[idx_new].key = str_offset;
+ file_entries_new->libs[idx_new].key
+ = str_offset + entry->lib->offset;
+ file_entries_new->libs[idx_new].value
+ = str_offset + entry->path->offset;
}
- size_t len = strlen (entry->lib) + 1;
- str = mempcpy (str, entry->lib, len);
- str_offset += len;
- /* Then the path. */
- if (opt_format != opt_format_new && entry->hwcap == 0)
- file_entries->libs[idx_old].value = str_offset + pad;
- if (opt_format != opt_format_old)
- file_entries_new->libs[idx_new].value = str_offset;
- len = strlen (entry->path) + 1;
- str = mempcpy (str, entry->path, len);
- str_offset += len;
/* Ignore entries with hwcap for old format. */
if (entry->hwcap == 0)
++idx_old;
@@ -511,7 +505,7 @@ save_cache (const char *cache_name)
extension_offset += pad;
extension_offset += file_entries_new_size;
}
- extension_offset += total_strlen;
+ extension_offset += strings_finalized.size;
extension_offset = roundup (extension_offset, 4); /* Provide alignment. */
if (opt_format != opt_format_old)
file_entries_new->extension_offset = extension_offset;
@@ -551,7 +545,8 @@ save_cache (const char *cache_name)
error (EXIT_FAILURE, errno, _("Writing of cache data failed"));
}
- if (write (fd, strings, total_strlen) != (ssize_t) total_strlen)
+ if (write (fd, strings_finalized.strings, strings_finalized.size)
+ != (ssize_t) strings_finalized.size)
error (EXIT_FAILURE, errno, _("Writing of cache data failed"));
if (opt_format != opt_format_old)
@@ -580,7 +575,7 @@ save_cache (const char *cache_name)
/* Free all allocated memory. */
free (file_entries_new);
free (file_entries);
- free (strings);
+ free (strings_finalized.strings);
while (entries)
{
@@ -596,14 +591,19 @@ void
add_to_cache (const char *path, const char *lib, int flags,
unsigned int osversion, uint64_t hwcap)
{
- size_t liblen = strlen (lib) + 1;
- size_t len = liblen + strlen (path) + 1;
- struct cache_entry *new_entry
- = xmalloc (sizeof (struct cache_entry) + liblen + len);
-
- new_entry->lib = memcpy ((char *) (new_entry + 1), lib, liblen);
- new_entry->path = new_entry->lib + liblen;
- snprintf (new_entry->path, len, "%s/%s", path, lib);
+ struct cache_entry *new_entry = xmalloc (sizeof (*new_entry));
+
+ struct stringtable_entry *path_interned;
+ {
+ char *p;
+ if (asprintf (&p, "%s/%s", path, lib) < 0)
+ error (EXIT_FAILURE, errno, _("Could not create library path"));
+ path_interned = stringtable_add (&strings, p);
+ free (p);
+ }
+
+ new_entry->lib = stringtable_add (&strings, lib);
+ new_entry->path = path_interned;
new_entry->flags = flags;
new_entry->osversion = osversion;
new_entry->hwcap = hwcap;
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