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scripts/versions.awk: Add strings and hashes to <first-versions.h>

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This generates new macros of this from:

They are useful for symbol lookups using _dl_lookup_direct.

Tested-by: Carlos O'Donell <carlos@redhat.com>
Reviewed-by: Carlos O'Donell <carlos@redhat.com>
This commit is contained in:
Florian Weimer 2021-05-10 10:31:41 +02:00
parent 9637e5669b
commit a64af8c9b6
1 changed files with 36 additions and 0 deletions
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36
scripts/versions.awk
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@ -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;