Nginx 1.1.4 can't build on Debian hurd-i386

[Cyril Lavier]

Hi.

For the Debian packaging purposes, I try to make Nginx working under the hurd-i386 kernel.

The error is the following.

gcc -c -pipe  -O -W -Wall -Wpointer-arith -Wno-unused-parameter -Wunused-function -Wunused-variable -Wunused-value -Werror -g  -I src/core -I src/event -I src/event/modules -I src/os/unix -I /usr/include/libxml2 -I objs -I src/http -I src/http/modules \
                -o objs/src/http/ngx_http_variables.o \
                src/http/ngx_http_variables.c
src/http/ngx_http_variables.c: In function ‘ngx_http_variable_realpath_root’:
src/http/ngx_http_variables.c:1160:37: error: ‘PATH_MAX’ undeclared (first use in this function)
src/http/ngx_http_variables.c:1160:37: note: each undeclared identifier is reported only once for each function it appears in
src/http/ngx_http_variables.c:1160:32: error: unused variable ‘real’ [-Werror=unused-variable]
cc1: all warnings being treated as error

Under hurd, there is no PATH_MAX variable defined in the limits.h kernel header, and in any other header.

In order to have this issue corrected, I decided to set the PATH_MAX at 4096 (which is the common value in most Linux based systems). And after this, the build is working fine.

I attached a patch which does the trick.

I would like this patch to be applied upstream, as it will benefit all distributions providing a hurd kernel.

I'm working on the last version (1.1.4), and it can be applied/adapted on any other serie (1.0.x and 0.8.x), as Nginx always failed to build under hurd-i386.

Thanks.

[Cyril Lavier]

Patch for setting the PATH_MAX value in src/os/unix/ngx_files.h

[Maxim Dounin]

(from ​http://mailman.nginx.org/pipermail/nginx/2011-September/029440.html)

There is a problem with this patch: nginx uses PATH_MAX to
allocate buffer used in realpath(), and POSIX claims:

: If resolved_name is not a null pointer and {PATH_MAX} is not
: defined as a constant in the <limits.h> header, the behavior is
: undefined.

​http://pubs.opengroup.org/onlinepubs/9699919799/functions/realpath.html

Just using arbitrary value instead of PATH_MAX will likely lead to
a problem. If we want to avoid usage of PATH_MAX the relevant
code should be converted to use realpath() with NULL as
resolved_name.

Other current use of PATH_MAX is for getcwd() buffer which should
be ok with any buffer size as getcwd() interface includes "size"
argument.

[www.google.com/accounts/o8/id?id=AItOawlrBgFmdbPtP7F_oAoxHZRcEzizzkclPEc]

Maybe nginx is just a wrong avenue and the patch should be rather pushed into hurd? ;-)

[Maxim Dounin]

I believe hurd behavior is POSIX-complaint here, PATH_MAX isn't required to be known. And there is a way to not require PATH_MAX to be defined, see above. I'll look into it as time permits, unless someone will be faster. :)

[Maxim Dounin]

In [4559/nginx]:

Fixed unconditional MAX_PATH usage (ticket #22).

POSIX doesn't require it to be defined, and Debian GNU/Hurd doesn't define
it. Note that if there is no MAX_PATH defined we have to use realpath()
with NULL argument and free() the result.

[Maxim Dounin]

Fix committed.