Read ld.so.conf the way ldconfig reads it

[v0ropaev]

processLdsoconfFile builds the set of directories the container's ldcache already covers, which is then subtracted from the directories the hook would add. A line it reads differently from ldconfig costs a directory, and the libraries in that directory are not found.

Five differences from parse_conf and parse_conf_include in glibc's elf/ldconfig.c:

Trailing comments. ldconfig ends every line at the first #, because the format has no quoting:

/* Because the file format does not know any form of quoting we
   can search forward for the next '#' character and if found
   make it terminating the line.  */
*strchrnul (line, '#') = '\0';

Here only a line starting with # was skipped, so /usr/local/lib # vendor libs became a directory of that whole name, and the same comment after an include left the pattern matching nothing.

A tab after include. The test was strings.HasPrefix(line, "include "); ldconfig accepts any blank (isblank (cp[7])). With a tab the line fell through and became a directory.

More than one pattern. ldconfig splits the remainder on blanks and globs each one:

cp += 8;
while ((dir = strsep (&cp, " \t")) != NULL)
  if (dir[0] != '\0')
    parse_conf_include (filename, lineno, do_chroot, dir);

The whole remainder went to a single filepath.Glob, and a pattern with a space in it matches nothing, so all of the patterns were lost rather than just the later ones.

Relative include patterns. ldconfig resolves them against the directory of the file that holds them:

if (pattern[0] != '/' && strchr (config_file, '/') != NULL)
  asprintf (&copy, "%s/%s", dirname (strdupa (config_file)), pattern);

filepath.Glob resolved them against the working directory. This runs after the pivot into the container root, so include ld.so.conf.d/*.conf in /etc/ld.so.conf looked for /ld.so.conf.d/*.conf.

hwcap lines. They became directories. ldconfig has ignored the directive since 2.33 and only reports it.

The TODO: How does ldconfig handle this? on the ErrBadPattern path is answered in a comment: a malformed pattern is no match and parsing carries on, which is what the code already did.

Tests

TestProcessLdsoconfFile, table-driven over a temporary directory, covering each of the five plus the cases that already worked, which are there as regression guards: a whole-line comment, an absolute include, a line that only looks like a directive (include alone, /includes, /hwcapsomething), and an include that matches nothing.

Six of the ten subtests fail on main, each with the wrong value from above. go test ./internal/... passes, go vet and gofmt clean.

[copy-pr-bot]

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