Pino Toscano
2014-Nov-21 16:17 UTC
Re: [Libguestfs] [PATCH 6/6] New API: btrfs_subvolume_show
On Friday 21 November 2014 13:18:00 Hu Tao wrote:> btrfs_subvolume_show shows the detailed information of a subvolume or > snapshot. > > Signed-off-by: Hu Tao <hutao@cn.fujitsu.com> > --- > daemon/btrfs.c | 167 +++++++++++++++++++++++++++++++++++++++++++++++++++ > generator/actions.ml | 9 +++ > src/MAX_PROC_NR | 2 +- > 3 files changed, 177 insertions(+), 1 deletion(-) > > diff --git a/daemon/btrfs.c b/daemon/btrfs.c > index e179b57..36ba588 100644 > --- a/daemon/btrfs.c > +++ b/daemon/btrfs.c > @@ -29,6 +29,7 @@ > #include "actions.h" > #include "optgroups.h" > #include "xstrtol.h" > +#include "c-ctype.h" > > GUESTFSD_EXT_CMD(str_btrfs, btrfs); > GUESTFSD_EXT_CMD(str_btrfstune, btrfstune); > @@ -813,3 +814,169 @@ do_btrfs_fsck (const char *device, int64_t superblock, int repair) > > return 0; > } > + > +char **do_btrfs_subvolume_show (const char *subvolume) > +{ > + const size_t MAX_ARGS = 64; > + const char *argv[MAX_ARGS]; > + size_t i = 0; > + CLEANUP_FREE char *subvolume_buf = NULL; > + CLEANUP_FREE char *err = NULL; > + CLEANUP_FREE char *out = NULL; > + char *p, *pend, *colon; > + DECLARE_STRINGSBUF (ret); > + int r; > + > + subvolume_buf = sysroot_path (subvolume); > + if (subvolume_buf == NULL) { > + reply_with_perror ("malloc"); > + return NULL; > + } > + > + ADD_ARG (argv, i, str_btrfs); > + ADD_ARG (argv, i, "subvolume"); > + ADD_ARG (argv, i, "show"); > + ADD_ARG (argv, i, subvolume_buf); > + ADD_ARG (argv, i, NULL); > + > + r = commandv (&out, &err, argv); > + if (r == -1) { > + reply_with_error ("%s: %s", subvolume, err); > + return NULL; > + } > + > + /* Output is: > + * > + * / > + * Name: root > + * uuid: c875169e-cf4e-a04d-9959-b667dec36234 > + * Parent uuid: - > + * Creation time: 2014-11-13 10:13:08 > + * Object ID: 256 > + * Generation (Gen): 6579 > + * Gen at creation: 5 > + * Parent: 5 > + * Top Level: 5 > + * Flags: - > + * Snapshot(s): > + * snapshots/test1 > + * snapshots/test2 > + * snapshots/test3 > + * > + */ > + > + p = out; > + > + p = strchr (p, '\n'); > + if (p) { > + *p = '\0'; > + p++; > + } > + else {Minor style note: } else { (also in other parts of this patch)> + reply_with_error ("truncated output");I'd print out anyway, to ease debugging failures a bit.> + return NULL; > + } > + > + /* If the path is the btrfs root, `btrfs subvolume show' reports: > + * <path> is btrfs root > + */ > + if (strstr(out, "is btrfs root") != NULL) {Take care of adding a space before parenthesis (also in other parts of this patch).> + reply_with_error ("%s is btrfs root", subvolume); > + return NULL; > + } > + > + /* The first line is the path of the subvolume. */ > + if (add_string (&ret, strdup("path")) == -1) {add_string duplicates the string, so you don't need to do that manually.> + return NULL; > + } > + if (add_string (&ret, out) == -1) { > + return NULL; > + } > + > + /* Read the lines and split into "key: value". */ > + while (*p) { > + /* leading spaces and tabs */ > + while (*p && c_isspace (*p)) p++;Properly indent such lines, so: while (*p && c_isspace (*p)) p++; (also, a minor optimization is to use ++p instead of p++, as it can avoid a temporary value)> + > + pend = strchrnul (p, '\n'); > + if (*pend == '\n') { > + *pend = '\0'; > + pend++; > + } > + > + if (!*p) continue; > + > + colon = strchr (p, ':'); > + if (colon) { > + *colon = '\0'; > + > + /* snapshot is special, see the output above */ > + if (strncmp(p, "Snapshot", sizeof("Snapshot") - 1) == 0) {Please use the STR* macros we have in src/guestfs-internal-all.h. Also, most probably it is better to match "Snapshot(s)", so if in the future a new field starting with "Snapshot" is added then it won't be mistaken for this multiline one.> + char *ss = NULL; > + > + if (add_string (&ret, p) == -1) { > + return NULL; > + }Single statements don't need curly brackets (also in other parts of the patch).> + > + /* each line is the path of a snapshot. */ > + p = pend; > + while (*p && strchr(p, ':') == NULL) {This will break once the output will have fields after Snapshot, as strchr(p, ':') will return a non-null value in one of the lines following the first line after the Snapshot one.> + while (*p && c_isspace (*p)) p++; > + pend = strchrnul (p, '\n'); > + if (*pend == '\n') { > + *pend = '\0'; > + pend++; > + }I see this code repeated already; I think it would be better to create a small helper function like: char *analyze_line (char *p, char **field, char **value) which would - destructively update p (setting null bytes, just like it is done now) - return in field the start of the field text - return in value, if present, the start of the value (after the colon) - return the pointer to the first character of the new line (or null, if none following) this way it is IMHO easier to iterate over the lines, and also to detect whether a line contains a field+value or just text.> + if (ss) { > + ss = realloc(ss, strlen(ss) + strlen(p));If realloc fails, the return value is null; this means that the following will leak ss in that case. Also, sounds like you are missing "," in the length of the string?> + strcat(ss, ",");Just save the length of ss before the realloc, and you can simply do ss[old_length_of_ss] = ',';> + strcat(ss, p);You can easily use memcpy here: memcpy (ss + old_length_of_ss + 1, p, strlen (p));> + } else { > + ss = strdup(p);Missing check for failed strdup.> + } > + > + p = pend; > + } > + > + if (ss) { > + if (add_string (&ret, ss) == -1) {This needs to be add_string_nodup.> + free(ss);No need to free ss here; theoretically add_string will take care of it, be it added to the stringbuf or freed on error.> + return NULL; > + } > + } > + else { > + if (add_string (&ret, strdup("")) == -1) { > + return NULL; > + } > + }If there are no elements for "Snapshot(s)", then it would be better to just not add an empty hash element.> + > + continue; > + } > + > + do { colon++; } while (*colon && c_isspace (*colon)); > + if (add_string (&ret, p) == -1) { > + return NULL; > + } > + if (add_string (&ret, colon) == -1) { > + return NULL; > + }At least from the example output added as comment, it seems that "not available" values might be "-" -- it'd just not add those, since as users of this API would still need to check for the existency of a certain key in the returned hash.> + } > + else { > + if (add_string (&ret, p) == -1) { > + return NULL; > + } > + if (add_string (&ret, "") == -1) { > + return NULL; > + }As above, I would not add elements with empty values in the hash.> + } > + > + p = pend; > + } > + > + if (end_stringsbuf (&ret) == -1) > + return NULL; > + > + return ret.argv; > + > +} > diff --git a/generator/actions.ml b/generator/actions.ml > index cf96039..24d3ecc 100644 > --- a/generator/actions.ml > +++ b/generator/actions.ml > @@ -12014,6 +12014,15 @@ This is the internal call which implements C<guestfs_lstatnslist>." }; > longdesc = "\ > Get the default subvolume or snapshot of a filesystem mounted at C<mountpoint>." }; > > + { defaults with > + name = "btrfs_subvolume_show"; > + style = RHashtable "btrfssubvolumeinfo", [Pathname "subvolume"], []; > + proc_nr = Some 425; > + optional = Some "btrfs"; camel_name = "BTRFSSubvolumeShow"; > + shortdesc = "show detailed information of the subvolume";"returns detailed information about the subvolume"> + longdesc = "\ > +show detailed information of the subvolume." };Like above, making sure it is properly capitalized at the beginning. -- Pino Toscano
On Fri, Nov 21, 2014 at 05:17:13PM +0100, Pino Toscano wrote:> On Friday 21 November 2014 13:18:00 Hu Tao wrote: > > btrfs_subvolume_show shows the detailed information of a subvolume or > > snapshot. > > > > Signed-off-by: Hu Tao <hutao@cn.fujitsu.com> > > --- > > daemon/btrfs.c | 167 +++++++++++++++++++++++++++++++++++++++++++++++++++ > > generator/actions.ml | 9 +++ > > src/MAX_PROC_NR | 2 +- > > 3 files changed, 177 insertions(+), 1 deletion(-) > > > > diff --git a/daemon/btrfs.c b/daemon/btrfs.c > > index e179b57..36ba588 100644 > > --- a/daemon/btrfs.c > > +++ b/daemon/btrfs.c > > @@ -29,6 +29,7 @@ > > #include "actions.h" > > #include "optgroups.h" > > #include "xstrtol.h" > > +#include "c-ctype.h" > > > > GUESTFSD_EXT_CMD(str_btrfs, btrfs); > > GUESTFSD_EXT_CMD(str_btrfstune, btrfstune); > > @@ -813,3 +814,169 @@ do_btrfs_fsck (const char *device, int64_t superblock, int repair) > > > > return 0; > > } > > + > > +char **do_btrfs_subvolume_show (const char *subvolume) > > +{ > > + const size_t MAX_ARGS = 64; > > + const char *argv[MAX_ARGS]; > > + size_t i = 0; > > + CLEANUP_FREE char *subvolume_buf = NULL; > > + CLEANUP_FREE char *err = NULL; > > + CLEANUP_FREE char *out = NULL; > > + char *p, *pend, *colon; > > + DECLARE_STRINGSBUF (ret); > > + int r; > > + > > + subvolume_buf = sysroot_path (subvolume); > > + if (subvolume_buf == NULL) { > > + reply_with_perror ("malloc"); > > + return NULL; > > + } > > + > > + ADD_ARG (argv, i, str_btrfs); > > + ADD_ARG (argv, i, "subvolume"); > > + ADD_ARG (argv, i, "show"); > > + ADD_ARG (argv, i, subvolume_buf); > > + ADD_ARG (argv, i, NULL); > > + > > + r = commandv (&out, &err, argv); > > + if (r == -1) { > > + reply_with_error ("%s: %s", subvolume, err); > > + return NULL; > > + } > > + > > + /* Output is: > > + * > > + * / > > + * Name: root > > + * uuid: c875169e-cf4e-a04d-9959-b667dec36234 > > + * Parent uuid: - > > + * Creation time: 2014-11-13 10:13:08 > > + * Object ID: 256 > > + * Generation (Gen): 6579 > > + * Gen at creation: 5 > > + * Parent: 5 > > + * Top Level: 5 > > + * Flags: - > > + * Snapshot(s): > > + * snapshots/test1 > > + * snapshots/test2 > > + * snapshots/test3 > > + * > > + */ > > + > > + p = out; > > + > > + p = strchr (p, '\n'); > > + if (p) { > > + *p = '\0'; > > + p++; > > + } > > + else { > > Minor style note: > } else { > > (also in other parts of this patch)Though I'm fine with it, but do we have coding style rules? I see both styles in existing codes.> > > + reply_with_error ("truncated output"); > > I'd print out anyway, to ease debugging failures a bit.Okay.> > > + return NULL; > > + } > > + > > + /* If the path is the btrfs root, `btrfs subvolume show' reports: > > + * <path> is btrfs root > > + */ > > + if (strstr(out, "is btrfs root") != NULL) { > > Take care of adding a space before parenthesis (also in other parts of > this patch).Okay.> > > + reply_with_error ("%s is btrfs root", subvolume); > > + return NULL; > > + } > > + > > + /* The first line is the path of the subvolume. */ > > + if (add_string (&ret, strdup("path")) == -1) { > > add_string duplicates the string, so you don't need to do that > manually.Okay.> > > + return NULL; > > + } > > + if (add_string (&ret, out) == -1) { > > + return NULL; > > + } > > + > > + /* Read the lines and split into "key: value". */ > > + while (*p) { > > + /* leading spaces and tabs */ > > + while (*p && c_isspace (*p)) p++; > > Properly indent such lines, so: > while (*p && c_isspace (*p)) > p++; > > (also, a minor optimization is to use ++p instead of p++, as it can > avoid a temporary value)Okay.> > > + > > + pend = strchrnul (p, '\n'); > > + if (*pend == '\n') { > > + *pend = '\0'; > > + pend++; > > + } > > + > > + if (!*p) continue; > > + > > + colon = strchr (p, ':'); > > + if (colon) { > > + *colon = '\0'; > > + > > + /* snapshot is special, see the output above */ > > + if (strncmp(p, "Snapshot", sizeof("Snapshot") - 1) == 0) { > > Please use the STR* macros we have in src/guestfs-internal-all.h. > > Also, most probably it is better to match "Snapshot(s)", so if in the > future a new field starting with "Snapshot" is added then it won't be > mistaken for this multiline one.Sounds good.> > > + char *ss = NULL; > > + > > + if (add_string (&ret, p) == -1) { > > + return NULL; > > + } > > Single statements don't need curly brackets (also in other parts of > the patch).I think it is better to document this one, too.> > > + > > + /* each line is the path of a snapshot. */ > > + p = pend; > > + while (*p && strchr(p, ':') == NULL) { > > This will break once the output will have fields after Snapshot, as > strchr(p, ':') will return a non-null value in one of the lines > following the first line after the Snapshot one.It is intended, so that we can parse properly possibly key:value pairs following "Snapshot(s)". Although a ':' in a snapshot path will hit it too, but people don't likely put a ':' in path.> > > + while (*p && c_isspace (*p)) p++; > > + pend = strchrnul (p, '\n'); > > + if (*pend == '\n') { > > + *pend = '\0'; > > + pend++; > > + } > > I see this code repeated already; I think it would be better to create > a small helper function like: > char *analyze_line (char *p, char **field, char **value) > which would > - destructively update p (setting null bytes, just like it is done now) > - return in field the start of the field text > - return in value, if present, the start of the value (after the colon) > - return the pointer to the first character of the new line (or null, > if none following) > this way it is IMHO easier to iterate over the lines, and also to detect > whether a line contains a field+value or just text.How to treat lines don't containing a colon? treat them as invalid line? or as value of key in previous line? Note this should be a general process.> > > + if (ss) { > > + ss = realloc(ss, strlen(ss) + strlen(p)); > > If realloc fails, the return value is null; this means that the > following will leak ss in that case. > > Also, sounds like you are missing "," in the length of the string? > > > + strcat(ss, ","); > > Just save the length of ss before the realloc, and you can simply do > ss[old_length_of_ss] = ','; > > > + strcat(ss, p); > > You can easily use memcpy here: > memcpy (ss + old_length_of_ss + 1, p, strlen (p)); > > > + } else { > > + ss = strdup(p); > > Missing check for failed strdup. > > > + } > > + > > + p = pend; > > + } > > + > > + if (ss) { > > + if (add_string (&ret, ss) == -1) { > > This needs to be add_string_nodup. > > > + free(ss); > > No need to free ss here; theoretically add_string will take care of it, > be it added to the stringbuf or freed on error.This is fail case.> > > + return NULL; > > + } > > + } > > + else { > > + if (add_string (&ret, strdup("")) == -1) { > > + return NULL; > > + } > > + } > > If there are no elements for "Snapshot(s)", then it would be better > to just not add an empty hash element. > > > + > > + continue; > > + } > > + > > + do { colon++; } while (*colon && c_isspace (*colon)); > > + if (add_string (&ret, p) == -1) { > > + return NULL; > > + } > > + if (add_string (&ret, colon) == -1) { > > + return NULL; > > + } > > At least from the example output added as comment, it seems that > "not available" values might be "-" -- it'd just not add those, since > as users of this API would still need to check for the existency of > a certain key in the returned hash.tune2fs-l lists keys with empty values, shouldn't we follow it?> > > + } > > + else { > > + if (add_string (&ret, p) == -1) { > > + return NULL; > > + } > > + if (add_string (&ret, "") == -1) { > > + return NULL; > > + } > > As above, I would not add elements with empty values in the hash. > > > + } > > + > > + p = pend; > > + } > > + > > + if (end_stringsbuf (&ret) == -1) > > + return NULL; > > + > > + return ret.argv; > > + > > +} > > diff --git a/generator/actions.ml b/generator/actions.ml > > index cf96039..24d3ecc 100644 > > --- a/generator/actions.ml > > +++ b/generator/actions.ml > > @@ -12014,6 +12014,15 @@ This is the internal call which implements C<guestfs_lstatnslist>." }; > > longdesc = "\ > > Get the default subvolume or snapshot of a filesystem mounted at C<mountpoint>." }; > > > > + { defaults with > > + name = "btrfs_subvolume_show"; > > + style = RHashtable "btrfssubvolumeinfo", [Pathname "subvolume"], []; > > + proc_nr = Some 425; > > + optional = Some "btrfs"; camel_name = "BTRFSSubvolumeShow"; > > + shortdesc = "show detailed information of the subvolume"; > > "returns detailed information about the subvolume" > > > + longdesc = "\ > > +show detailed information of the subvolume." }; > > Like above, making sure it is properly capitalized at the beginning.sure. Thank you for reviewing!> > -- > Pino Toscano
Pino Toscano
2014-Nov-24 17:17 UTC
Re: [Libguestfs] [PATCH 6/6] New API: btrfs_subvolume_show
On Monday 24 November 2014 16:22:53 Hu Tao wrote:> On Fri, Nov 21, 2014 at 05:17:13PM +0100, Pino Toscano wrote: > > On Friday 21 November 2014 13:18:00 Hu Tao wrote: > > > btrfs_subvolume_show shows the detailed information of a subvolume > > > or > > > snapshot. > > > > > > Signed-off-by: Hu Tao <hutao@cn.fujitsu.com> > > > --- > > > > > > daemon/btrfs.c | 167 > > > +++++++++++++++++++++++++++++++++++++++++++++++++++ > > > generator/actions.ml | 9 +++ > > > src/MAX_PROC_NR | 2 +- > > > 3 files changed, 177 insertions(+), 1 deletion(-) > > > > > > diff --git a/daemon/btrfs.c b/daemon/btrfs.c > > > index e179b57..36ba588 100644 > > > --- a/daemon/btrfs.c > > > +++ b/daemon/btrfs.c > > > @@ -29,6 +29,7 @@ > > > > > > #include "actions.h" > > > #include "optgroups.h" > > > #include "xstrtol.h" > > > > > > +#include "c-ctype.h" > > > > > > GUESTFSD_EXT_CMD(str_btrfs, btrfs); > > > GUESTFSD_EXT_CMD(str_btrfstune, btrfstune); > > > > > > @@ -813,3 +814,169 @@ do_btrfs_fsck (const char *device, int64_t > > > superblock, int repair)> > > > > return 0; > > > > > > } > > > > > > + > > > +char **do_btrfs_subvolume_show (const char *subvolume) > > > +{ > > > + const size_t MAX_ARGS = 64; > > > + const char *argv[MAX_ARGS]; > > > + size_t i = 0; > > > + CLEANUP_FREE char *subvolume_buf = NULL; > > > + CLEANUP_FREE char *err = NULL; > > > + CLEANUP_FREE char *out = NULL; > > > + char *p, *pend, *colon; > > > + DECLARE_STRINGSBUF (ret); > > > + int r; > > > + > > > + subvolume_buf = sysroot_path (subvolume); > > > + if (subvolume_buf == NULL) { > > > + reply_with_perror ("malloc"); > > > + return NULL; > > > + } > > > + > > > + ADD_ARG (argv, i, str_btrfs); > > > + ADD_ARG (argv, i, "subvolume"); > > > + ADD_ARG (argv, i, "show"); > > > + ADD_ARG (argv, i, subvolume_buf); > > > + ADD_ARG (argv, i, NULL); > > > + > > > + r = commandv (&out, &err, argv); > > > + if (r == -1) { > > > + reply_with_error ("%s: %s", subvolume, err); > > > + return NULL; > > > + } > > > + > > > + /* Output is: > > > + * > > > + * / > > > + * Name: root > > > + * uuid: > > > c875169e-cf4e-a04d-9959-b667dec36234 + * Parent uuid: > > > - > > > + * Creation time: 2014-11-13 10:13:08 > > > + * Object ID: 256 > > > + * Generation (Gen): 6579 > > > + * Gen at creation: 5 > > > + * Parent: 5 > > > + * Top Level: 5 > > > + * Flags: - > > > + * Snapshot(s): > > > + * snapshots/test1 > > > + * snapshots/test2 > > > + * snapshots/test3 > > > + * > > > + */ > > > + > > > + p = out; > > > + > > > + p = strchr (p, '\n'); > > > + if (p) { > > > + *p = '\0'; > > > + p++; > > > + } > > > + else { > > > > Minor style note: > > } else { > > > > (also in other parts of this patch) > > Though I'm fine with it, but do we have coding style rules? I see both > styles in existing codes.>From what I see, «} else {» is more common.> > > + > > > + /* each line is the path of a snapshot. */ > > > + p = pend; > > > + while (*p && strchr(p, ':') == NULL) { > > > > This will break once the output will have fields after Snapshot, as > > strchr(p, ':') will return a non-null value in one of the lines > > following the first line after the Snapshot one. > > It is intended, so that we can parse properly possibly key:value pairs > following "Snapshot(s)". Although a ':' in a snapshot path will hit > it too, but people don't likely put a ':' in path.Well, that's not what would happen: "p" points to the first character of the line after the "Snapshot(s)" one, and strchr() will try to find ':' until the end of the string, not stopping at newlines and such. Let's say the output is something like: Name: root uuid: c875169e-cf4e-a04d-9959-b667dec36234 Parent uuid: - Creation time: 2014-11-13 10:13:08 Object ID: 256 Generation (Gen): 6579 Gen at creation: 5 Parent: 5 Top Level: 5 Flags: - Snapshot(s): snapshots/test1 snapshots/test2 snapshots/test3 Other attribute: - p would be at: snapshots/test1 ^- here, while strchr(p, ':') == NULL) would be Other attribute: - ^- here, so skipping all the multi-line value.> > > + while (*p && c_isspace (*p)) p++; > > > + pend = strchrnul (p, '\n'); > > > + if (*pend == '\n') { > > > + *pend = '\0'; > > > + pend++; > > > + } > > > > I see this code repeated already; I think it would be better to > > create> > > a small helper function like: > > char *analyze_line (char *p, char **field, char **value) > > > > which would > > - destructively update p (setting null bytes, just like it is done now) > > - return in field the start of the field text > > - return in value, if present, the start of the value (after the colon) > > - return the pointer to the first character of the new line (or null, > > if none following) > > > > this way it is IMHO easier to iterate over the lines, and also to > > detect whether a line contains a field+value or just text. > > How to treat lines don't containing a colon? treat them as invalid > line? or as value of key in previous line? Note this should be a > general process.field pointing at their non-blank start, and value as null.> > > + free(ss); > > > > No need to free ss here; theoretically add_string will take care of > > it, be it added to the stringbuf or freed on error. > > This is fail case.I don't understand what you mean here, can you please be more verbose?> > > + > > > + continue; > > > + } > > > + > > > + do { colon++; } while (*colon && c_isspace (*colon)); > > > + if (add_string (&ret, p) == -1) { > > > + return NULL; > > > + } > > > + if (add_string (&ret, colon) == -1) { > > > + return NULL; > > > + } > > > > At least from the example output added as comment, it seems that > > "not available" values might be "-" -- it'd just not add those, > > since > > as users of this API would still need to check for the existency of > > a certain key in the returned hash. > > tune2fs-l lists keys with empty values, shouldn't we follow it?Do you have an example of them? I haven't used tune2fs-l much myself, but I don't remember having seen empty values in its output. -- Pino Toscano
On Fri, Nov 21, 2014 at 05:17:13PM +0100, Pino Toscano wrote: <...>> > + while (*p && c_isspace (*p)) p++; > > + pend = strchrnul (p, '\n'); > > + if (*pend == '\n') { > > + *pend = '\0'; > > + pend++; > > + } > > I see this code repeated already; I think it would be better to create > a small helper function like: > char *analyze_line (char *p, char **field, char **value)perhaps an extra delimiter parameter?> which would > - destructively update p (setting null bytes, just like it is done now) > - return in field the start of the field text > - return in value, if present, the start of the value (after the colon) > - return the pointer to the first character of the new line (or null, > if none following) > this way it is IMHO easier to iterate over the lines, and also to detect > whether a line contains a field+value or just text.Regards, Hu