diff options
| -rw-r--r-- | src/lib/gamma-linux-drm.c | 135 |
1 files changed, 81 insertions, 54 deletions
diff --git a/src/lib/gamma-linux-drm.c b/src/lib/gamma-linux-drm.c index cf98115..2619e0d 100644 --- a/src/lib/gamma-linux-drm.c +++ b/src/lib/gamma-linux-drm.c @@ -191,68 +191,95 @@ int libgamma_linux_drm_site_restore(libgamma_site_state_t* restrict this) */ static int figure_out_card_open_error(const char* pathname) { + gid_t supplemental_groups[NGROUPS_MAX]; + struct group* group; + struct stat attr; + int i, n; + + /* Check which the device exists. */ if ((errno == ENXIO) || (errno == ENODEV)) return LIBGAMMA_NO_SUCH_PARTITION; + /* If we did not get access permission, figure out why. */ - if (errno == EACCES) - { + + if (errno != EACCES) + /* If we could not figure out what + went wrong, just return the error + we got. */ + return LIBGAMMA_ERRNO_SET; + #define __test(R, W) ((attr.st_mode & (R | W)) == (R | W)) - gid_t supplemental_groups[NGROUPS_MAX]; - struct group* group; - struct stat attr; - int i, n; - - - /* Get permission requirement for the file. */ - if (stat(pathname, &attr) < 0) - return errno == EACCES ? LIBGAMMA_NO_SUCH_PARTITION : LIBGAMMA_ERRNO_SET; - - /* Test owner's, group's and others' permissions. */ - if ((attr.st_uid == geteuid() && __test(S_IRUSR, S_IWUSR)) || - (attr.st_gid == getegid() && __test(S_IRGRP, S_IWGRP)) || - __test(S_IROTH, S_IWOTH)) - return LIBGAMMA_DEVICE_ACCESS_FAILED; - - /* The group should be "video", but perhaps - it is "root" to restrict users. */ - if (attr.st_gid == 0 /* root group */ || __test(S_IRGRP, S_IWGRP)) - return LIBGAMMA_DEVICE_RESTRICTED; - - - /* Get the user's supplemental group membership list. */ - if ((n = getgroups(NGROUPS_MAX, supplemental_groups)) < 0) - return LIBGAMMA_ERRNO_SET; - - /* Test whether any of the supplemental - group should be satisfactory. */ - for (i = 0; i < n; i++) - if (supplemental_groups[i] == attr.st_gid) - break; - - /* If one of the supplemental groups - should be satisfactory, then we - do not know anything more than - that access failed. */ - if (i != n) - return LIBGAMMA_DEVICE_ACCESS_FAILED; - /* Otherwise, try to get the name of - the group that is required and - report the missing group membership. */ - errno = 0; - group = getgrgid(attr.st_gid); /* TODO: Not thread-safe. */ - libgamma_group_gid = attr.st_gid; - libgamma_group_name = group != NULL ? group->gr_name : NULL; - return LIBGAMMA_DEVICE_REQUIRE_GROUP; -#undef __test - } + /* Get permission requirement for the file. */ + if (stat(pathname, &attr) < 0) + return errno == EACCES ? LIBGAMMA_NO_SUCH_PARTITION : LIBGAMMA_ERRNO_SET; + + /* Test owner's, group's and others' permissions. */ + if ((attr.st_uid == geteuid() && __test(S_IRUSR, S_IWUSR)) || + (attr.st_gid == getegid() && __test(S_IRGRP, S_IWGRP)) || + __test(S_IROTH, S_IWOTH)) + return LIBGAMMA_DEVICE_ACCESS_FAILED; + + /* The group should be "video", but perhaps + it is "root" to restrict users. */ + if (attr.st_gid == 0 /* root group */ || __test(S_IRGRP, S_IWGRP)) + return LIBGAMMA_DEVICE_RESTRICTED; + + + /* Get the user's supplemental group membership list. */ + if ((n = getgroups(NGROUPS_MAX, supplemental_groups)) < 0) + return LIBGAMMA_ERRNO_SET; + + /* Test whether any of the supplemental + group should be satisfactory. */ + for (i = 0; i < n; i++) + if (supplemental_groups[i] == attr.st_gid) + break; + + /* If one of the supplemental groups + should be satisfactory, then we + do not know anything more than + that access failed. */ + if (i != n) + return LIBGAMMA_DEVICE_ACCESS_FAILED; + + /* Otherwise, try to get the name of + the group that is required and + report the missing group membership. */ +#if _POSIX_C_SOURCE >= 1 || _XOPEN_SOURCE || _BSD_SOURCE || _SVID_SOURCE || _POSIX_SOURCE + /* Thread-safe. */ + { + static __thread char buf[1024]; /* My output of `sysconf(_SC_GETGR_R_SIZE_MAX)`. */ + struct group _grp; + + errno = getgrgid_r(attr.st_gid, &_grp, buf, sizeof(buf) / sizeof(char), &group); + if (errno == ERANGE) + { + /* The lenght of the group's name is absurdly long, degrade to thread-unsafe. */ + errno = 0; + group = getgrgid(attr.st_gid); + } + else if (errno) + return LIBGAMMA_ERRNO_SET; + } +#else +# ifdef __GCC__ +# pragma GCC diagnostic push +# pragma GCC diagnostic ignored "-Wcpp" +# warning figure_out_card_open_error is not thread-safe +# pragma GCC diagnostic pop +# endif + /* Not thread-safe. */ + errno = 0; + group = getgrgid(attr.st_gid); +#endif - /* If we could not figure out what - went wrong, just return the error - we got. */ - return LIBGAMMA_ERRNO_SET; + libgamma_group_gid = attr.st_gid; + libgamma_group_name = group != NULL ? group->gr_name : NULL; + return LIBGAMMA_DEVICE_REQUIRE_GROUP; +#undef __test } |