G__tempfile() lacks perror support

[neteler]

(The problem arises from r.hants Addon use, reported on grass-user)

Using r.hants (derived from r.series) on almost 600 raster maps generates an "ERROR: no temp files available" on Linux 64bit. The input maps have been registered with r.external:

D2/3: G_file_name(): path = /home/user/grassdata/latlong/cloro/GDAL
D2/3: G_file_name(): path = /home/user/grassdata/latlong/cloro/.tmp/localhost.localdomain/12772.6
D2/3: G_file_name(): path = /home/user/grassdata/latlong/cloro/.tmp/localhost.localdomain/12772.7
D2/3: G_file_name(): path = /home/user/grassdata/latlong/cloro/GDAL
D2/3: G_file_name(): path = /home/user/grassdata/latlong/cloro/.tmp/localhost.localdomain/12772.8
D2/3: G_file_name(): path = /home/user/grassdata/latlong/cloro/.tmp/localhost.localdomain/12772.9
ERROR: no temp files available
GRASS 7.1.svn (latlong_wgs84):~ >

For a better error message, perror() should be used:

in lib/gis/tempfile.c

char *G__tempfile(int pid)
{

[...]
    do {
    int uniq = G_counter_next(&unique);
    sprintf(name, "%d.%d", pid, uniq);
    G_file_name(path, element, name, G_mapset());
    }
    while (access(path, F_OK) == 0);
[...]

We need to explain the error with perror() as done in

in lib/gis/mapset.c

    if (access(mapset, F_OK) != 0) {
    perror("access");
    G_fatal_error(_("MAPSET <%s> not available"), mapset);

Anyone able to modify the while() loop in lib/gis/tempfile.c accordingly?

[glynn]

Replying to neteler:

For a better error message, perror() should be used:

Ideally, strerror() (or similar) should be used, and the string included in the error message. Otherwise, the additional details will be omitted from any logfile ($GIS_ERROR_LOG) or email message ($GRASS_ERROR_MAIL).

Except, strerror() isn't thread-safe (it returns a pointer to a static buffer). POSIX.1-2001 specifies strerror_r(), which requires the caller to supply a buffer. Windows doesn't have that, but it has strerror_s (same functionality, different argument order). So we'd need configure checks.

[mmetz]

Replying to neteler:

(The problem arises from r.hants Addon use, reported on grass-user)

Using r.hants (derived from r.series) on almost 600 raster maps generates an "ERROR: no temp files available" on Linux 64bit.

r.series with the same number of input maps should fail with the same error. r.hants has been derived from r.series, and both modules have the -z flag (Don't keep files open) which should avoid this problem.

[mmetz]

Replying to mmetz:

Replying to neteler:

(The problem arises from r.hants Addon use, reported on grass-user)

Using r.hants (derived from r.series) on almost 600 raster maps generates an "ERROR: no temp files available" on Linux 64bit.

r.series with the same number of input maps should fail with the same error. r.hants has been derived from r.series, and both modules have the -z flag (Don't keep files open) which should avoid this problem.

Sorry, the -z flag does not help here because r.hants creates a new output map for each input map, and these need to be kept open. For 600 input maps, the hard limit of the number of open files is usually exceeded.

[neteler]

Replying to glynn:

Replying to neteler:

For a better error message, perror() should be used:

Ideally, strerror() (or similar) should be used, and the string included in the error message.

Done by mmetz in r60148 and related.

[glynn]

Replying to neteler:

Ideally, strerror() (or similar) should be used, and the string included in the error message.

Done by mmetz in r60148 and related.

For robustness, errno should be copied to a local variable immediately after the failed call, e.g.:

    fcb->null_fd = creat(tempname, 0666);
    if (fcb->null_fd < 0) {
        int err = errno;
        ...
	G_fatal_error(_("No temp files available: %s"), strerror(err));
    }

Otherwise, it may be modified by an intervening call (specifically, close() can modify errno).

[martinl]

In 69223:

Gtempfile() lacks perror support (see #2278)

[martinl]

In 69224:

Gtempfile() lacks perror support (see #2278, backport r69223 from trunk)

[martinl]

In 69225:

Gtempfile() lacks perror support (fix #2278, backport r69223 from trunk)