Commit [1] 164bc10d "btrfs-progs: add musl compatibility for printf
format %pV" added a logic to detect the presence of the glibc
<printf.h> header, and if present, to use the
register_printf_specifier() and register_printf_modifier() functions.
The original intent (as the commit log suggests), was to support the
musl libc, which does not provides this <printf.h> header.
When compiling with another libc, such as uClibc-ng, btrfs-progs fail
to build with error:
common/messages.c: In function 'print_va_format':
common/messages.c:51:19: error: 'const struct printf_info' has no member named 'user'
51 | if (!(info->user & va_modifier))
| ^~
common/messages.c: In function 'btrfs_no_printk':
common/messages.c:76:17: warning: implicit declaration of function 'register_printf_specifier'; did you mean 'register_printf_function'? [-Wimplicit-function-declaration]
76 | register_printf_specifier('V', print_va_format,
| ^~~~~~~~~~~~~~~~~~~~~~~~~
| register_printf_function
common/messages.c:78:31: warning: implicit declaration of function 'register_printf_modifier'; did you mean 'register_printf_function'? [-Wimplicit-function-declaration]
78 | va_modifier = register_printf_modifier(L"p");
| ^~~~~~~~~~~~~~~~~~~~~~~~
| register_printf_function
This is because uClibc-ng provides a <printf.h> header, but not the
register_printf_specifier() and register_printf_modifier() functions.
See [2]. It mainly includes register_printf_function(). uClibc-ng
emulates an older glibc behavior. Glibc added support for printf user
elements in commit [3] (first included in glibc-2.10, in 2009). Checking
only the <printf.h> is not sufficient.
This commit fixes this build issue by refining the detection logic of
the <printf.h> functions required by btrfs-progs.
[1] 164bc10dfc
[2] https://gogs.waldemar-brodkorb.de/oss/uclibc-ng/src/v1.0.49/include/printf.h
[3] https://sourceware.org/git/?p=glibc.git;a=commitdiff;h=9d26efa90c6dcbcd6b3e586c9927b6058ef4d529
Pull-request: #843
Signed-off-by: Julien Olivain <ju.o@free.fr>
Signed-off-by: David Sterba <dsterba@suse.com>
9fdb8d7469