[v2,1/2] scripts/versions.awk: Add strings and hashes to <first-versions.h>
Commit Message
This generates new macros of this from:
#define FIRST_VERSION_libc___pthread_mutex_lock_STRING "GLIBC_2.2.5"
#define FIRST_VERSION_libc___pthread_mutex_lock_HASH 0x9691a75
They are useful for symbol lookups using _dl_lookup_direct.
---
scripts/versions.awk | 36 ++++++++++++++++++++++++++++++++++++
1 file changed, 36 insertions(+)
@@ -32,6 +32,29 @@ BEGIN {
sort = "sort -t. -k 1,1 -k 2n,2n -k 3 > " tmpfile;
}
+# GNU awk does not implement the ord and chr functions.
+# <https://www.gnu.org/software/gawk/manual/html_node/Ordinal-Functions.html>
+# says that they are "written very nicely", using code similar to what
+# is included here.
+function chr(c) {
+ return sprintf("%c", c)
+}
+
+BEGIN {
+ for (c = 1; c < 127; c++) {
+ ord_table[chr(c)] = c;
+ }
+}
+
+function ord(c) {
+ if (ord_table[c]) {
+ return ord_table[c];
+ } else {
+ printf("Invalid character reference: '%c'\n", c) > "/dev/stderr";
+ ++lossage;
+ }
+}
+
# Remove comment lines.
/^ *#/ {
next;
@@ -90,6 +113,17 @@ function close_and_move(name, real_name) {
system(move_if_change " " name " " real_name " >&2");
}
+# ELF hash, for use with symbol versions.
+function elf_hash(s, i, acc) {
+ acc = 0;
+ for (i = 1; i <= length(s); ++i) {
+ acc = and(lshift(acc, 4) + ord(substr(s, i, 1)), 0xffffffff);
+ top = and(acc, 0xf0000000);
+ acc = and(xor(acc, rshift(top, 24)), compl(top));
+ }
+ return acc;
+}
+
# Now print the accumulated information.
END {
close(sort);
@@ -145,6 +179,8 @@ END {
&& oldver ~ "^GLIBC_[0-9]" \
&& sym ~ "^[A-Za-z0-9_]*$") {
ver_val = oldver;
+ printf("#define %s_STRING \"%s\"\n", first_ver_macro, ver_val) > first_ver_header;
+ printf("#define %s_HASH 0x%x\n", first_ver_macro, elf_hash(ver_val)) > first_ver_header;
gsub("\\.", "_", ver_val);
printf("#define %s %s\n", first_ver_macro, ver_val) > first_ver_header;
first_ver_seen[first_ver_macro] = 1;