8.4.0 fails to build on cross-compiled android ARM

[12932]

I did this

Build curl:

configure: Configured to build curl/libcurl:

  Host setup:       arm-unknown-linux-androideabi
  Install prefix:   /usr/local
  Compiler:         arm-linux-androideabi-gcc -std=gnu11
   CFLAGS:          -D__ANDROID_API__=21 -fPIC -Werror-implicit-function-declaration -O2 -Wno-system-headers
   CPPFLAGS:        -isystem /home/ubuntu/dev/curl/src/../interface/include -isystem /home/ubuntu/dev/curl/src/../interface/include/ANDROIDARM -isystem /home/ubuntu/dev/curl/src/../interface/include/LINUX -fPIC
   LDFLAGS:         -L/home/ubuntu/dev/curl/src/../interface/lib/ANDROIDARM -fPIC
   LIBS:            -lssl -lcrypto -ldl

  curl version:     8.4.0
  SSL:              enabled (OpenSSL)
  SSH:              no      (--with-{libssh,libssh2})
  zlib:             no      (--with-zlib)
  brotli:           no      (--with-brotli)
  zstd:             no      (--with-zstd)
  GSS-API:          no      (--with-gssapi)
  GSASL:            no      (libgsasl not found)
  TLS-SRP:          enabled
  resolver:         POSIX threaded
  IPv6:             no      (--enable-ipv6)
  Unix sockets:     enabled
  IDN:              no      (--with-{libidn2,winidn})
  Build libcurl:    Shared=no, Static=yes
  Built-in manual:  no      (--enable-manual)
  --libcurl option: enabled (--disable-libcurl-option)
  Verbose errors:   enabled (--disable-verbose)
  Code coverage:    disabled
  SSPI:             no      (--enable-sspi)
  ca cert bundle:   no
  ca cert path:     no
  ca fallback:      no
  LDAP:             no      (--enable-ldap / --with-ldap-lib / --with-lber-lib)
  LDAPS:            no      (--enable-ldaps)
  RTSP:             enabled
  RTMP:             no      (--with-librtmp)
  PSL:              no      (libpsl not found)
  Alt-svc:          enabled (--disable-alt-svc)
  Headers API:      enabled (--disable-headers-api)
  HSTS:             enabled (--disable-hsts)
  HTTP1:            enabled (internal)
  HTTP2:            no      (--with-nghttp2, --with-hyper)
  HTTP3:            no      (--with-ngtcp2 --with-nghttp3, --with-quiche, --with-msh3)
  ECH:              no      (--enable-ech)
  WebSockets:       no      (--enable-websockets)
  Protocols:        DICT FILE FTP FTPS GOPHER GOPHERS HTTP HTTPS IMAP IMAPS MQTT POP3 POP3S RTSP SMB SMBS SMTP SMTPS TELNET TFTP
  Features:         AsynchDNS HSTS HTTPS-proxy Largefile NTLM SSL TLS-SRP UnixSockets alt-svc threadsafe

Making all in lib
xmake[1]: Entering directory `/home/ubuntu/dev/curl/src/build.ANDROIDARM.P/lib'
xmake[2]: Entering directory `/home/ubuntu/dev/curl/src/build.ANDROIDARM.P/lib'
  CC       libcurl_la-altsvc.lo
  CC       libcurl_la-amigaos.lo
  CC       libcurl_la-asyn-ares.lo
  CC       libcurl_la-asyn-thread.lo
  CC       libcurl_la-base64.lo
  CC       libcurl_la-bufq.lo
  CC       libcurl_la-bufref.lo
  CC       libcurl_la-c-hyper.lo
  CC       libcurl_la-cf-h1-proxy.lo
  CC       libcurl_la-cf-h2-proxy.lo
  CC       libcurl_la-cf-haproxy.lo
  CC       libcurl_la-cf-https-connect.lo
  CC       libcurl_la-cf-socket.lo
  CC       libcurl_la-cfilters.lo
  CC       libcurl_la-conncache.lo
  CC       libcurl_la-connect.lo
  CC       libcurl_la-content_encoding.lo
  CC       libcurl_la-cookie.lo
  CC       libcurl_la-curl_addrinfo.lo
  CC       libcurl_la-curl_des.lo
  CC       libcurl_la-curl_endian.lo
  CC       libcurl_la-curl_fnmatch.lo
  CC       libcurl_la-curl_get_line.lo
  CC       libcurl_la-curl_gethostname.lo
  CC       libcurl_la-curl_gssapi.lo
  CC       libcurl_la-curl_memrchr.lo
  CC       libcurl_la-curl_multibyte.lo
  CC       libcurl_la-curl_ntlm_core.lo
  CC       libcurl_la-curl_ntlm_wb.lo
  CC       libcurl_la-curl_path.lo
  CC       libcurl_la-curl_range.lo
  CC       libcurl_la-curl_rtmp.lo
  CC       libcurl_la-curl_sasl.lo
  CC       libcurl_la-curl_sspi.lo
  CC       libcurl_la-curl_threads.lo
  CC       libcurl_la-curl_trc.lo
  CC       libcurl_la-dict.lo
  CC       libcurl_la-doh.lo
  CC       libcurl_la-dynbuf.lo
  CC       libcurl_la-dynhds.lo
  CC       libcurl_la-easy.lo
  CC       libcurl_la-easygetopt.lo
  CC       libcurl_la-easyoptions.lo
  CC       libcurl_la-escape.lo
  CC       libcurl_la-file.lo
  CC       libcurl_la-fileinfo.lo
  CC       libcurl_la-fopen.lo
  CC       libcurl_la-formdata.lo
/home/ubuntu/dev/curl/src/curl-8.4.0/lib/formdata.c: In function 'fseeko_wrapper':
/home/ubuntu/dev/curl/src/curl-8.4.0/lib/formdata.c:796:3: error: implicit declaration of function 'fseeko' [-Werror=implicit-function-declaration]
   return fseeko(stream, (off_t)offset, whence);
   ^
cc1: some warnings being treated as errors
xmake[2]: *** [libcurl_la-formdata.lo] Error 1
xmake[2]: Leaving directory `/home/ubuntu/dev/curl/src/build.ANDROIDARM.P/lib'
xmake[1]: *** [all] Error 2
xmake[1]: Leaving directory `/home/ubuntu/dev/curl/src/build.ANDROIDARM.P/lib'
make: *** [all-recursive] Error 1
xmake: *** [ANDROIDARMP.OBJ/dummy] Error 2
[Make] (E) Program terminated. Errors previously reported

I expected the following

Curl to build successfully

curl/libcurl version

NA

operating system

Linux 7a4b33d7e1d4 5.15.90.1-microsoft-standard-WSL2 #1 SMP Fri Jan 27 02:56:13 UTC 2023 x86_64 x86_64 x86_64 GNU/Linux

[dfandrich]

Does Android/bionic actually have fseeko? If so, where is it defined?

[12932]

ubuntu@7a4b33d7e1d4:/$ nm -D /android-ndk-arm/sysroot/usr/lib/libc.so | grep fseeko
0000a851 T fseeko

[cajus]

Nearly the same output in the CI here:

formdata.c:796:10: error: call to undeclared function 'fseeko'; ISO C99 and later do not support implicit function declarations [-Wimplicit-function-declaration]
  return fseeko(stream, (off_t)offset, whence);
         ^
formdata.c:796:10: note: did you mean 'fseek'?
/home/dev/.conan/data/android_ndk_installer/r26/bje/stable/package/b925f19ad6eb509f29bf6c0a5b52e2a00411ce69/toolchains/llvm/prebuilt/linux-x86_64/sysroot/usr/include/stdio.h:215:5: note: 'fseek' declared here
int fseek(FILE* _Nonnull __fp, long __offset, int __whence);
    ^
1 error generated.

Seems to depend on the target min SDK version: https://stackoverflow.com/questions/55571842/android-error-use-of-undeclared-identifier-fseeko

Snippet from stdio.h:

int fseek(FILE* _Nonnull __fp, long __offset, int __whence);
long ftell(FILE* _Nonnull __fp);

/* See https://android.googlesource.com/platform/bionic/+/master/docs/32-bit-abi.md */
#if defined(__USE_FILE_OFFSET64)

#if __ANDROID_API__ >= 24
int fgetpos(FILE* _Nonnull __fp, fpos_t* _Nonnull __pos) __RENAME(fgetpos64) __INTRODUCED_IN(24);
int fsetpos(FILE* _Nonnull __fp, const fpos_t* _Nonnull __pos) __RENAME(fsetpos64) __INTRODUCED_IN(24);
int fseeko(FILE* _Nonnull __fp, off_t __offset, int __whence) __RENAME(fseeko64) __INTRODUCED_IN(24);
off_t ftello(FILE* _Nonnull __fp) __RENAME(ftello64) __INTRODUCED_IN(24);
#endif /* __ANDROID_API__ >= 24 */

[cajus]

As a quick and dirty workaround, I skipped the fseeko check for android.

diff -Naur a/CMakeLists.txt b/CMakeLists.txt
--- a/CMakeLists.txt	2023-10-09 08:21:51.000000000 +0200
+++ b/CMakeLists.txt	2023-10-11 12:53:58.055399342 +0200
@@ -1180,7 +1180,9 @@
 check_symbol_exists(freeaddrinfo   "${CURL_INCLUDES}" HAVE_FREEADDRINFO)
 check_symbol_exists(pipe           "${CURL_INCLUDES}" HAVE_PIPE)
 check_symbol_exists(ftruncate      "${CURL_INCLUDES}" HAVE_FTRUNCATE)
-check_symbol_exists(fseeko         "${CURL_INCLUDES};stdio.h" HAVE_FSEEKO)
+if(CMAKE_SYSTEM_NAME NOT STREQUAL Android)
+    check_symbol_exists(fseeko         "${CURL_INCLUDES};stdio.h" HAVE_FSEEKO)
+endif()
 check_symbol_exists(_fseeki64      "${CURL_INCLUDES};stdio.h" HAVE__FSEEKI64)
 check_symbol_exists(getpeername    "${CURL_INCLUDES}" HAVE_GETPEERNAME)
 check_symbol_exists(getsockname    "${CURL_INCLUDES}" HAVE_GETSOCKNAME)
diff -Naur a/configure.ac b/configure.ac
--- a/configure.ac	2023-10-05 09:58:50.000000000 +0200
+++ b/configure.ac	2023-10-11 13:13:07.486490432 +0200
@@ -3577,6 +3577,14 @@
     ;;
 esac
 
+case $host in
+   *android*)
+     ac_cv_func_fseeko=no
+     skipcheck_fseeko=yes
+     AC_MSG_NOTICE([skip check for fseeko on android])
+    ;;
+esac
+
 AC_CHECK_DECLS([getpwuid_r], [], [AC_DEFINE(HAVE_DECL_GETPWUID_R_MISSING, 1, "Set if getpwuid_r() declaration is missing")],
         [[#include <pwd.h>
           #include <sys/types.h>]])

[vszakats]

Another workaround is configuring with: cmake -DHAVE_FSEEKO=0 (and possibly export ac_cv_func_fseeko='no' for autotools.)

I wonder why the detection and use turn out differently.

Does this help perventing false-detection with CMake?:

diff --git a/CMakeLists.txt b/CMakeLists.txt
index 1b19c681d..23cd906dc 100644
--- a/CMakeLists.txt
+++ b/CMakeLists.txt
@@ -1180,7 +1180,7 @@ check_symbol_exists(getifaddrs     "${CURL_INCLUDES};stdlib.h" HAVE_GETIFADDRS)
 check_symbol_exists(freeaddrinfo   "${CURL_INCLUDES}" HAVE_FREEADDRINFO)
 check_symbol_exists(pipe           "${CURL_INCLUDES}" HAVE_PIPE)
 check_symbol_exists(ftruncate      "${CURL_INCLUDES}" HAVE_FTRUNCATE)
-check_symbol_exists(fseeko         "${CURL_INCLUDES};stdio.h" HAVE_FSEEKO)
+check_symbol_exists(fseeko         "stdio.h" HAVE_FSEEKO)
 check_symbol_exists(_fseeki64      "${CURL_INCLUDES};stdio.h" HAVE__FSEEKI64)
 check_symbol_exists(getpeername    "${CURL_INCLUDES}" HAVE_GETPEERNAME)
 check_symbol_exists(getsockname    "${CURL_INCLUDES}" HAVE_GETSOCKNAME)

[vvb2060]

https://android.googlesource.com/platform/bionic/+/refs/heads/main/docs/32-bit-abi.md
for 32 bit (defined __USE_FILE_OFFSET64), fseeko requires minapi >= 24, 64 bit don’t have this issue.
I think there is something wrong with the check code.

[vszakats]

Please try #12086 (comment) and report if it changes detection results.

It could clear the question if anything in CURL_INCLUDES might
skew detection results the wrong way.

[bagder]

@12932 this still seems to imply that configure found the fseeko function which is why it was enabled. Does config.log reveal any clues as to why it would do wrong for that specific function and not the others?

[cajus]

configure:43527: checking for fseeko
configure:43527: /home/dev/.conan/data/android_ndk_installer/r26/bje/stable/package/b925f19ad6eb509f29bf6c0a5b52e2a00411ce69/toolchains/llvm/prebuilt/linux-x86_64/bin/armv7a-linux-androideabi23-clang -o conftest -O3 --sysroot=/home/dev/.conan/data/android_ndk_installer/r26/bje/stable/package/b925f19ad6eb509f29bf6c0a5b52e2a00411ce69/toolchains/llvm/prebuilt/linux-x86_64/sysroot -fPIC -fPIC -Qunused-arguments -Wno-pointer-bool-conversion -I/home/dev/.conan/data/openssl/3.0.11/bje/stable/package/c078f6735e61e43f18849088a49c08c26c3fd3ec/include -I/home/dev/.conan/data/zlib/1.3/bje/stable/package/f0c177dad580ee9cdcb0b0da457d467f5bdab4ab/include -DNDEBUG -I/home/dev/.conan/data/zlib/1.3/bje/stable/package/f0c177dad580ee9cdcb0b0da457d467f5bdab4ab/include -I/home/dev/.conan/data/openssl/3.0.11/bje/stable/package/c078f6735e61e43f18849088a49c08c26c3fd3ec/include --sysroot=/home/dev/.conan/data/android_ndk_installer/r26/bje/stable/package/b925f19ad6eb509f29bf6c0a5b52e2a00411ce69/toolchains/llvm/prebuilt/linux-x86_64/sysroot -L/home/dev/.conan/data/java_installer/19.0.2/bje/stable/package/44fcf6b9a7fb86b2586303e3db40189d3b511830/lib -L/home/dev/.conan/data/openssl/3.0.11/bje/stable/package/c078f6735e61e43f18849088a49c08c26c3fd3ec/lib -L/home/dev/.conan/data/zlib/1.3/bje/stable/package/f0c177dad580ee9cdcb0b0da457d467f5bdab4ab/lib -Wl,--hash-style=both -L/home/dev/.conan/data/zlib/1.3/bje/stable/package/f0c177dad580ee9cdcb0b0da457d467f5bdab4ab/lib -L/home/dev/.conan/data/openssl/3.0.11/bje/stable/package/c078f6735e61e43f18849088a49c08c26c3fd3ec/lib conftest.c -lssl -lcrypto -lz -lssl -lcrypto -lz >&5
configure:43527: $? = 0
configure:43527: result: yes

Maybe the required defines for the minimum targed sdk are missing there, so that it finds it?

[bagder]

Maybe the required defines for the minimum targed sdk are missing there, so that it finds it?

The check links a test program that uses the symbol, and the linking works. So the function is definitely present there. So yes it could be a problem with the define, if the define causes the symbol to somehow get redefined and make it not found by the linker.

[cajus]

But:

$ /home/dev/.conan/data/android_ndk_installer/r26/bje/stable/package/b925f19ad6eb509f29bf6c0a5b52e2a00411ce69/toolchains/llvm/prebuilt/linux-x86_64/bin/armv7a-linux-androideabi23-clang -dM -E - < /dev/null | grep ANDROID
#define __ANDROID_API__ __ANDROID_MIN_SDK_VERSION__
#define __ANDROID_MIN_SDK_VERSION__ 23
#define __ANDROID__ 1

and the check in stdio.h is based on

#if __ANDROID_API__ >= 24

But seems to trigger. It also triggers if I write <= 24, and I failed to output the value of __ANDROID_API__ in stdio.h using #pragma message. No messages are printed at all.

[bagder]

Those are just defines that don't change the fseeko name though. So they will not prevent the linker from finding the fseeko function that you evidently have.

[cajus]

Doesn't it? __ANDROID_API__ is __ANDROID_MIN_SDK_VERSION__, which is 23 in my case. The visibility of fseeko in stdio.h is coupled to __ANDROID_API__. If I change that one to #if 0, it compiles.

[bagder]

The visibility of fseeko in stdio.h

The prototype being provided in that header only changes if you get a compiler warning or not, it does not prevent the function from being able to link.