Merge branch 'patch-1' into 'master'

Clean up everything and add lots of new functions

I hope everything here is okay. I fixed some bugs in existing functions (mostly wrong prototypes or off-by-one errors) and formatted everything to a consistent style. If you'd like me to adjust the style, that's no problem. It wasn't very consistent to start with (within the code, and compared to the documentation).

*I added specific notes you may want to comment on to some of the commit messages.*

Major features:
* Pass correct `argv[0]` in loader
* Intercept `readlink("/proc/self/exe")` to allow re-exec
* Add almost all reasonable-to-implement functions in LSB 5.0.0 core generic libc. Remaining functions are:
  - Impossible-to-implement: sigreturn
  - Not useful: reentrant random (`*rand48_r`, etc.), argz, envz, pmap, rpc (clnt_*, svc*, xdr*), bindresvport
  - Got tired of it: checked wchar
* Add additional functions used by android and its NDK tools (clang, cmake, lldb, ninja, etc.).

At this point, I am able to run Android Studio with the bundled prebuilt JDK, and compile, install, and run an android application (including one with native libraries) on a real device, with only a few minor issues:
* must export `LD_LIBRARY_PATH=/opt/android-studio/jre/jre/lib/amd64/server` because musl and glibc interpret the variable differently with regards to `dlopen`. This is something that has to be patched in musl builds of openjdk, so it's not a gcompat issue.
* ld.bfd fails to parse the argument `--sysroot=/path`, but can parse `--sysroot /path`. So there's some difference with `getopt_long_only` (or getopt in general). May be a bug, may be just an API difference. May be it can be patched up.
* LLDB fails to connect to the android phone for native debugging -- I haven't tried it on glibc yet, so it may not be a gcompat issue at all (may be a phone or the app issue).

I'd be happy to send some documentation later.

See merge request !1

1 files changed, 81 insertions, 44 deletions

diff --git a/libgcompat/pwd.c b/libgcompat/pwd.c
index 2e09aea..34c5d7b 100644
--- a/libgcompat/pwd.c
+++ b/libgcompat/pwd.c
@@ -1,55 +1,92 @@
 /* some musl versions incorrectly mark fgetpwent() as a GNU extension */
 #define _GNU_SOURCE
-
-#include <stdio.h>
-#include <errno.h>
-#include <pwd.h>
-#include <string.h>
-
-
-int getpwent_r(struct passwd *pwbuf, char *buf, size_t buflen, struct passwd **pwbufp) {
-	struct passwd *pwd;
-
-	if (pwbufp == NULL || pwbuf == NULL)
-		return ERANGE;
-
-	if (buflen < 1)
-		return ERANGE;
-
-	if (buf != NULL)
-		*buf = '\0';
-
-	if ((pwd = getpwent()) == NULL) {
-		*pwbufp = NULL;
+#include <assert.h>  /* assert */
+#include <errno.h>   /* ENOENT, ERANGE */
+#include <pthread.h> /* pthread_mutex_* */
+#include <pwd.h>     /* fgetpwent, getpwent, struct passwd */
+#include <stddef.h>  /* NULL, size_t */
+#include <stdio.h>   /* FILE */
+#include <string.h>  /* memcpy, stpcpy, strlcpy, strlen */
+
+static pthread_mutex_t pwent_mutex = PTHREAD_MUTEX_INITIALIZER;
+
+static int __fgetpwent_r(FILE *stream, struct passwd *pwd, char *buf,
+                         size_t len, struct passwd **result)
+{
+	struct passwd *pwtmp;
+	char *cursor = buf, *end = buf + len;
+
+	*result = NULL;
+	pthread_mutex_lock(&pwent_mutex);
+	pwtmp = stream != NULL ? fgetpwent(stream) : getpwent();
+	if (pwtmp == NULL) {
+		pthread_mutex_unlock(&pwent_mutex);
 		return ENOENT;
 	}
-
-	memcpy(pwbuf, pwd, sizeof(*pwd));
-	*pwbufp = pwbuf;
+	memcpy(pwd, pwtmp, sizeof(*pwd));
+	if (pwtmp->pw_name != NULL) {
+		pwd->pw_name = cursor;
+		cursor += strlcpy(cursor, pwtmp->pw_name, end - cursor) + 1;
+		if (cursor > end) {
+			goto err_unlock;
+		}
+	}
+	if (pwtmp->pw_passwd != NULL) {
+		pwd->pw_passwd = cursor;
+		cursor += strlcpy(cursor, pwtmp->pw_passwd, end - cursor) + 1;
+		if (cursor > end) {
+			goto err_unlock;
+		}
+	}
+	if (pwtmp->pw_gecos != NULL) {
+		pwd->pw_gecos = cursor;
+		cursor += strlcpy(cursor, pwtmp->pw_gecos, end - cursor) + 1;
+		if (cursor > end) {
+			goto err_unlock;
+		}
+	}
+	if (pwtmp->pw_dir != NULL) {
+		pwd->pw_dir = cursor;
+		cursor += strlcpy(cursor, pwtmp->pw_dir, end - cursor) + 1;
+		if (cursor > end) {
+			goto err_unlock;
+		}
+	}
+	if (pwtmp->pw_shell != NULL) {
+		pwd->pw_shell = cursor;
+		cursor += strlcpy(cursor, pwtmp->pw_shell, end - cursor) + 1;
+		if (cursor > end) {
+			goto err_unlock;
+		}
+	}
+	pthread_mutex_unlock(&pwent_mutex);
+	*result = pwd;
 
 	return 0;
-}
-
-
-int fgetpwent_r(FILE *filp, struct passwd *pwbuf, char *buf, size_t buflen, struct passwd **pwbufp) {
-	struct passwd *pwd;
-
-	if (pwbufp == NULL || pwbuf == NULL)
-		return ERANGE;
-
-	if (buflen < 1)
-		return ERANGE;
 
-	if (buf != NULL)
-		*buf = '\0';
+err_unlock:
+	pthread_mutex_unlock(&pwent_mutex);
+	return ERANGE;
+}
 
-	if ((pwd = fgetpwent(filp)) == NULL) {
-		*pwbufp = NULL;
-		return ENOENT;
-	}
+/**
+ * Get passwd file entry.
+ */
+int fgetpwent_r(FILE *stream, struct passwd *pwd, char *buf, size_t len,
+                struct passwd **result)
+{
+	assert(stream != NULL);
 
-	memcpy(pwbuf, pwd, sizeof(*pwd));
-	*pwbufp = pwbuf;
+	return fgetpwent_r(stream, pwd, buf, len, result);
+}
 
-	return 0;
+/**
+ * Get user database entry.
+ *
+ * LSB 5.0: LSB-Core-generic/baselib-getpwent-r-1.html
+ */
+int getpwent_r(struct passwd *pwd, char *buf, size_t len,
+               struct passwd **result)
+{
+	return __fgetpwent_r(NULL, pwd, buf, len, result);
 }