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author | A. Wilcox <awilcox@wilcox-tech.com> | 2018-02-01 22:05:36 +0000 |
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committer | A. Wilcox <awilcox@wilcox-tech.com> | 2018-02-01 22:05:36 +0000 |
commit | 88815225fdabe7fa862f1c07abfcc971fdf5b04e (patch) | |
tree | 7aaae7c04fcf06aea85505fc028f476a131b9c50 /libgcompat/readlink.c | |
parent | c545f7393f0a10c182c2c085a36d7099b9c07a7f (diff) | |
parent | 78722ef403ffadcb78917e93e1859d43b9bf9df5 (diff) | |
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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
Diffstat (limited to 'libgcompat/readlink.c')
-rw-r--r-- | libgcompat/readlink.c | 85 |
1 files changed, 85 insertions, 0 deletions
diff --git a/libgcompat/readlink.c b/libgcompat/readlink.c new file mode 100644 index 0000000..63def96 --- /dev/null +++ b/libgcompat/readlink.c @@ -0,0 +1,85 @@ +#include <dlfcn.h> +#include <fcntl.h> +#include <limits.h> +#include <stddef.h> +#include <stdlib.h> +#include <string.h> +#include <unistd.h> + +#ifndef LINKER +#error LINKER must be defined +#endif + +static char exe[PATH_MAX], *linker; +static ssize_t (*real_readlink)(const char *, char *, size_t); + +ssize_t readlink(const char *path, char *buf, size_t len) +{ + if (real_readlink == NULL) { + real_readlink = dlsym(RTLD_NEXT, "readlink"); + if (real_readlink == NULL) { + return -1; + } + } + + if (!strcmp(path, "/proc/self/exe")) { + int fd; + + if (exe[0] == '\0') { + if (linker == NULL) { + linker = realpath(LINKER, NULL); + if (linker == NULL) { + return -1; + } + } + if (real_readlink(path, exe, sizeof(exe)) < 1) { + goto fail; + } + if (!strcmp(exe, linker)) { + char c; + int arg = 0; + ssize_t arglen; + + fd = open("/proc/self/cmdline", + O_RDONLY | O_CLOEXEC); + if (fd < 0) { + goto fail; + } + /* Skip the --argv0/--preload ldso args. + * This number must be kept in sync with the + * argument order in loader/loader.c */ + while (arg < 5) { + if (read(fd, &c, 1) != 1) { + goto fail_close; + } + if (c == '\0') { + ++arg; + } + } + /* Read the executable path from the cmdline. */ + arglen = read(fd, exe, sizeof(exe)); + if (arglen < 1) { + goto fail_close; + } + close(fd); + /* Ensure the path exists, fits, and has NUL. */ + if (exe[0] == '\0') { + goto fail; + } + if (strnlen(exe, arglen) == (size_t) arglen) { + goto fail; + } + } + } + + return stpncpy(buf, exe, len) - buf; + + fail_close: + close(fd); + fail: + exe[0] = '\0'; + return -1; + } + + return real_readlink(path, buf, len); +} |