On Wednesday 18 February 2015 15:13:21 you wrote: > On Wed, Feb 18, 2015 at 12:09 PM, Laszlo Papp <[email protected]> wrote: > > On Wed, Feb 18, 2015 at 11:00 AM, tito <[email protected]> wrote: > >> On Wednesday 18 February 2015 09:14:42 you wrote: > >> > >>> On Wed, Feb 18, 2015 at 8:09 AM, Laszlo Papp <[email protected]> wrote: > >> > >>> > On Wed, Feb 18, 2015 at 7:34 AM, Laszlo Papp <[email protected]> wrote: > >> > >>> >> I thought about this, too, when writing the patch, but I rejected it > >>> >> because > >> > >>> >> it is not simpler, in fact more complex, it is also not the right layer > >>> >> for > >> > >>> >> the change. In addition, it would also be somewhat slower to execute. > >> > >>> > > >> > >>> > Just to elaborate a bit more on this as I was sending that on my phone: > >> > >>> > > >> > >>> > 1) Why do you want to make a few lines more simpler to spare a few > >> > >>> > lines to introduce bad implementation and slower operation? > >> > >>> > > >> > >>> > 2) Also, the update_passwd function already has all the structure to > >> > >>> > handle this through the file, name and member variables. It looks like > >> > >>> > the natural place to utilize the existing infrastructure. > >> > >>> > > >> > >>> > 3) Basically, you would go through the groups once in the embedded > >> > >>> > list and then you would go through again rather than just doing the > >> > >>> > thing correct in the first place at the first iteration. So basically, > >> > >>> > you would have double embedded list iteration. Even if the group list > >> > >>> > was stored in memory for _each_ user, it would still slightly be > >> > >>> > slower and I would argue that wasting memory for potentially a big > >> > >>> > file could defeat busybox's purpose in the first place. Anyway, > >> > >>> > busybox's design goal should be to be as fast as possible. Personal > >> > >>> > preferences should neither slow it down, nor make it use more memory > >> > >>> > than needed to achieve the task. > >> > >>> > >> > >>> I would actually even go further than that, namely: the same-named > >> > >>> group deletion should probably be integrated into my loop so that one > >> > >>> embedded iteration could deal with the group file changes rather than > >> > >>> two separate. > >> > >>> > >> > >> > >> > >> Hi, > >> > >> > >> > >> you can try to write a patch, but i suspect that it could be difficult > >> > >> with the current update_password interface without breaking the > >> > >> deluser from group use case. > >> > >> If you opt for doing the changes in deluser instead some useful > >> > >> get_groups code is in the id applet and could be moved to libbb as > >> > >> function. This will of course be slower as more iterations are done > >> > >> through the passwd/group files. > > > > I start to think that the best approach would be neither to use your > > idea, nor mine, but actually a separate function doing the thing fast. > > See my updated patch below which almost works, but it remains slow if > > I try to inject the new code into the "line based" read and write > > concept. Why don't we just create a new function? > > Actually, the locking and swapping logic would be common anyway which > already resides in update_passwd, so if that reusable component is not > moved to a separate function to be reused, we could use put our > conditional magic into the while loop. I am preparing with that change > now. > > By the way, why does busybox use /etc/file+ and /etc/file- for this > logic as opposed to ... say: mkstemp?
So other instances of programs that want to change file know that it is in use (file+ existing) and wait? > > commit 813e3db073aca7a55b9f3d4650055e7d1ed768b4 > > Author: Laszlo Papp <[email protected]> > > Date: Tue Feb 17 20:01:04 2015 +0000 > > > > Delete the user from all the groups for user deletion > > > > diff --git a/libbb/update_passwd.c b/libbb/update_passwd.c > > index a30af6f..24f949b 100644 > > --- a/libbb/update_passwd.c > > +++ b/libbb/update_passwd.c > > @@ -62,6 +62,8 @@ static void check_selinux_update_passwd(const char > > *username) > > only if CONFIG_PASSWD=y and applet_name[0] == 'p' like in passwd > > or if CONFIG_CHPASSWD=y and applet_name[0] == 'c' like in chpasswd > > > > + 8) delete a user from all groups : update_passwd(FILE, NULL, NULL, MEMBER) > > + > > This function does not validate the arguments fed to it > > so the calling program should take care of that. > > > > @@ -81,7 +83,7 @@ int FAST_FUNC update_passwd(const char *filename, > > FILE *new_fp; > > char *fnamesfx; > > char *sfx_char; > > - char *name_colon; > > + char *name_colon = 0; > > unsigned user_len; > > int old_fd; > > int new_fd; > > @@ -99,13 +101,15 @@ int FAST_FUNC update_passwd(const char *filename, > > if (filename == NULL) > > return ret; > > > > - check_selinux_update_passwd(name); > > + if (name) check_selinux_update_passwd(name); > > > > /* New passwd file, "/etc/passwd+" for now */ > > fnamesfx = xasprintf("%s+", filename); > > sfx_char = &fnamesfx[strlen(fnamesfx)-1]; > > - name_colon = xasprintf("%s:", name); > > - user_len = strlen(name_colon); > > + if (name) { > > + name_colon = xasprintf("%s:", name); > > + user_len = strlen(name_colon); > > + } > > > > if (shadow) > > old_fp = fopen(filename, "r+"); > > @@ -159,6 +163,19 @@ int FAST_FUNC update_passwd(const char *filename, > > bb_perror_msg("warning: can't lock '%s'", filename); > > lock.l_type = F_UNLCK; > > > > + if (!name && member) { > > + struct group* g; > > + while ((g = getgrent())) { > > + char **s= g->gr_mem; > > + char **d = s; > > + while (*s) { > > + if (strcmp(*s, member)) { *d = *s; ++d; } > > + ++s; > > + } > > + *d = 0; > > + } > > + } > > + > > /* Read current password file, write updated /etc/passwd+ */ > > changed_lines = 0; > > while (1) { > > @@ -167,7 +184,7 @@ int FAST_FUNC update_passwd(const char *filename, > > line = xmalloc_fgetline(old_fp); > > if (!line) /* EOF/error */ > > break; > > - if (strncmp(name_colon, line, user_len) != 0) { > > + if (!name_colon || strncmp(name_colon, line, user_len) != > > 0) { > > fprintf(new_fp, "%s\n", line); > > goto next; > > } > > @@ -176,7 +193,7 @@ int FAST_FUNC update_passwd(const char *filename, > > cp = line + user_len; /* move past name: */ > > > > #if ENABLE_FEATURE_ADDUSER_TO_GROUP || ENABLE_FEATURE_DEL_USER_FROM_GROUP > > - if (member) { > > + if (name && member) { > > /* It's actually /etc/group+, not /etc/passwd+ */ > > if (ENABLE_FEATURE_ADDUSER_TO_GROUP > > && applet_name[0] == 'a' > > @@ -240,7 +257,7 @@ int FAST_FUNC update_passwd(const char *filename, > > > > if (changed_lines == 0) { > > #if ENABLE_FEATURE_ADDUSER_TO_GROUP || ENABLE_FEATURE_DEL_USER_FROM_GROUP > > - if (member) { > > + if (name && member) { > > if (ENABLE_ADDGROUP && applet_name[0] == 'a') > > bb_error_msg("can't find %s in %s", > > name, filename); > > if (ENABLE_DELGROUP && applet_name[0] == 'd') > > diff --git a/loginutils/deluser.c b/loginutils/deluser.c > > index 01a9386..8219569 100644 > > --- a/loginutils/deluser.c > > +++ b/loginutils/deluser.c > > @@ -82,6 +82,9 @@ int deluser_main(int argc, char **argv) > > do_delgroup: > > /* "delgroup GROUP" or "delgroup USER GROUP" */ > > if (do_deluser < 0) { /* delgroup after deluser? */ > > + pfile = bb_path_group_file; > > + if (update_passwd(pfile, NULL, NULL, name) == -1) > > + return EXIT_FAILURE; > > gr = getgrnam(name); > > if (!gr) > > return EXIT_SUCCESS; > > @@ -99,7 +102,6 @@ int deluser_main(int argc, char **argv) > > } > > //endpwent(); > > } > > - pfile = bb_path_group_file; > > if (ENABLE_FEATURE_SHADOWPASSWDS) > > sfile = bb_path_gshadow_file; > > } >
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