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library: improve and/or standardize 'errno' management

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With older library logic having been modified to avoid
using those potentially deadly alloc.h routines, while
improving 'errno' handling, we're ready to standardize
and enhance newlib's approach to any potential errors.

In so doing, we'll establish the following objectives:

. . . . . . . . . . . . . functions returning an 'int'
. an error will be indicated by a negative number that
is always the inverse of some well known errno.h value

. . . . . . . . . . . functions returning an 'address'
. any error will be indicated by a NULL return pointer
with the actual reason found in the formal errno value

And, when errno is manipulated directly we will strive
to do so whenever possible within those routines which
have been declared with PROCPS_EXPORT. In other words,
in the user callable functions defined in source last.

[ But, that won't always be possible. In particular, ]
[ all the 'read_failed' functions will sometimes set ]
[ 'errno' so that they can serve callers returning a ]
[ NULL or an int without duplicating a lot of logic. ]

[ Also, that includes one subordinate function which ]
[ was called by 'read_failed' in the <slabinfo> API. ]

------------------------------------------------------
Along the way, several additional miscellaneous issues
were addressed. They're listed here now for posterity.

. the '-1' return value passed outside the library was
eliminated since it would erroneously equate to -EPERM

. the stacks_fetch functions in <diskstats> and <stat>
weren't checked for their possible minus return values

. hash create was not checked in <meminfo> or <vmstat>

. fixed 'new' function faulty parm check in <slabinfo>

Signed-off-by: Jim Warner <james.warner@comcast.net>
This commit is contained in:
Jim Warner
2017-11-18 00:00:00 -05:00
committed by Craig Small
parent 7453f8719b
commit 06be33b43e
6 changed files with 262 additions and 203 deletions
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81
proc/diskstats.c
View File

@ -390,13 +390,13 @@ static int node_update (
if (!target) {
if (!(target = malloc(sizeof(struct dev_node))))
return -ENOMEM;
return 0;
memcpy(target, source, sizeof(struct dev_node));
// let's not distort the deltas when a new node is created ...
memcpy(&target->old, &target->new, sizeof(struct dev_data));
node_classify(target);
node_add(info, target);
return 0;
return 1;
}
// remember history from last time around ...
memcpy(&source->old, &target->new, sizeof(struct dev_data));
@ -405,7 +405,7 @@ static int node_update (
source->next = target->next;
// finally 'update' the existing node struct ...
memcpy(target, source, sizeof(struct dev_node));
return 0;
return 1;
} // end: node_update
@ -517,14 +517,14 @@ static inline int diskstats_items_check_failed (
*/
if (numitems < 1
|| (void *)items < (void *)(unsigned long)(2 * DISKSTATS_logical_end))
return -1;
return 1;
for (i = 0; i < numitems; i++) {
// a diskstats_item is currently unsigned, but we'll protect our future
if (items[i] < 0)
return -1;
return 1;
if (items[i] >= DISKSTATS_logical_end)
return -1;
return 1;
}
return 0;
@ -539,7 +539,7 @@ static inline int diskstats_items_check_failed (
* Read the data out of /proc/diskstats putting the information
* into the supplied info structure
*
* Returns: 0 on success, negative on error
* Returns: 0 on success, 1 on error
*/
static int diskstats_read_failed (
struct diskstats_info *info)
@ -552,10 +552,10 @@ static int diskstats_read_failed (
if (!info->diskstats_fp
&& (!(info->diskstats_fp = fopen(DISKSTATS_FILE, "r"))))
return -errno;
return 1;
if (fseek(info->diskstats_fp, 0L, SEEK_SET) == -1)
return -errno;
return 1;
info->old_stamp = info->new_stamp;
info->new_stamp = time(NULL);
@ -581,13 +581,12 @@ static int diskstats_read_failed (
, &node.new.io_wtime);
if (rc != 14) {
if (errno != 0)
return -errno;
return -EIO;
errno = ERANGE;
return 1;
}
node.stamped = info->new_stamp;
if ((rc = node_update(info, &node)))
return rc;
if (!node_update(info, &node))
return 1; // here, errno was set to ENOMEM
}
return 0;
@ -672,7 +671,7 @@ static int diskstats_stacks_fetch (
}
if (!info->fetch_ext.extents) {
if (!(ext = diskstats_stacks_alloc(&info->fetch_ext, n_alloc)))
return -ENOMEM;
return -1; // here, errno was set to ENOMEM
memset(info->fetch.anchor, 0, sizeof(void *) * n_alloc);
memcpy(info->fetch.anchor, ext->stacks, sizeof(void *) * n_alloc);
diskstats_itemize_stacks_all(&info->fetch_ext);
@ -687,7 +686,7 @@ static int diskstats_stacks_fetch (
n_alloc += STACKS_INCR;
if ((!(info->fetch.anchor = realloc(info->fetch.anchor, sizeof(void *) * n_alloc)))
|| (!(ext = diskstats_stacks_alloc(&info->fetch_ext, STACKS_INCR))))
return -1;
return -1; // here, errno was set to ENOMEM
memcpy(info->fetch.anchor + n_inuse, ext->stacks, sizeof(void *) * STACKS_INCR);
}
diskstats_assign_results(info->fetch.anchor[n_inuse], node);
@ -703,7 +702,7 @@ static int diskstats_stacks_fetch (
if (n_saved < n_inuse + 1) {
n_saved = n_inuse + 1;
if (!(info->fetch.results.stacks = realloc(info->fetch.results.stacks, sizeof(void *) * n_saved)))
return -ENOMEM;
return -1;
}
memcpy(info->fetch.results.stacks, info->fetch.anchor, sizeof(void *) * n_inuse);
info->fetch.results.stacks[n_inuse] = NULL;
@ -722,14 +721,14 @@ static int diskstats_stacks_reconfig_maybe (
int numitems)
{
if (diskstats_items_check_failed(this, items, numitems))
return -EINVAL;
return -1;
/* is this the first time or have things changed since we were last called?
if so, gotta' redo all of our stacks stuff ... */
if (this->numitems != numitems + 1
|| memcmp(this->items, items, sizeof(enum diskstats_item) * numitems)) {
// allow for our DISKSTATS_logical_end
if (!(this->items = realloc(this->items, sizeof(enum diskstats_item) * (numitems + 1))))
return -ENOMEM;
return -1; // here, errno was set to ENOMEM
memcpy(this->items, items, sizeof(enum diskstats_item) * numitems);
this->items[numitems] = DISKSTATS_logical_end;
this->numitems = numitems + 1;
@ -757,11 +756,9 @@ PROCPS_EXPORT int procps_diskstats_new (
struct diskstats_info **info)
{
struct diskstats_info *p;
int rc;
if (info == NULL)
return -EINVAL;
if (!(p = calloc(1, sizeof(struct diskstats_info))))
return -ENOMEM;
@ -771,9 +768,9 @@ PROCPS_EXPORT int procps_diskstats_new (
1) ensure there will be no problems with subsequent access |
2) make delta results potentially useful, even if 1st time |
3) elimnate need for history distortions 1st time 'switch' | */
if ((rc = diskstats_read_failed(p))) {
if (diskstats_read_failed(p)) {
procps_diskstats_unref(&p);
return rc;
return -errno;
}
*info = p;
@ -803,6 +800,8 @@ PROCPS_EXPORT int procps_diskstats_unref (
(*info)->refcount--;
if ((*info)->refcount < 1) {
int errno_sav = errno;
if ((*info)->diskstats_fp) {
fclose((*info)->diskstats_fp);
(*info)->diskstats_fp = NULL;
@ -830,6 +829,8 @@ PROCPS_EXPORT int procps_diskstats_unref (
free(*info);
*info = NULL;
errno = errno_sav;
return 0;
}
return (*info)->refcount;
@ -846,10 +847,12 @@ PROCPS_EXPORT struct diskstats_result *procps_diskstats_get (
struct dev_node *node;
time_t cur_secs;
errno = EINVAL;
if (info == NULL)
return NULL;
if (item < 0 || item >= DISKSTATS_logical_end)
return NULL;
errno = 0;
/* we will NOT read the diskstat file with every call - rather, we'll offer
a granularity of 1 second between reads ... */
@ -860,12 +863,13 @@ PROCPS_EXPORT struct diskstats_result *procps_diskstats_get (
}
info->get_this.item = item;
// with 'get', we must NOT honor the usual 'noop' guarantee
// if (item > DISKSTATS_noop)
info->get_this.result.ul_int = 0;
// with 'get', we must NOT honor the usual 'noop' guarantee
info->get_this.result.ul_int = 0;
if (!(node = node_get(info, name)))
if (!(node = node_get(info, name))) {
errno = ENXIO;
return NULL;
}
Item_table[item].setsfunc(&info->get_this, node);
return &info->get_this;
@ -884,18 +888,20 @@ PROCPS_EXPORT struct diskstats_reap *procps_diskstats_reap (
enum diskstats_item *items,
int numitems)
{
errno = EINVAL;
if (info == NULL || items == NULL)
return NULL;
if (0 > diskstats_stacks_reconfig_maybe(&info->fetch_ext, items, numitems))
return NULL;
return NULL; // here, errno may be overridden with ENOMEM
errno = 0;
if (info->fetch_ext.dirty_stacks)
diskstats_cleanup_stacks_all(&info->fetch_ext);
if (diskstats_read_failed(info))
return NULL;
diskstats_stacks_fetch(info);
if (0 > diskstats_stacks_fetch(info))
return NULL;
info->fetch_ext.dirty_stacks = 1;
return &info->fetch.results;
@ -917,11 +923,12 @@ PROCPS_EXPORT struct diskstats_stack *procps_diskstats_select (
{
struct dev_node *node;
errno = EINVAL;
if (info == NULL || items == NULL)
return NULL;
if (0 > diskstats_stacks_reconfig_maybe(&info->select_ext, items, numitems))
return NULL;
return NULL; // here, errno may be overridden with ENOMEM
errno = 0;
if (!info->select_ext.extents
&& (!diskstats_stacks_alloc(&info->select_ext, 1)))
@ -932,8 +939,10 @@ PROCPS_EXPORT struct diskstats_stack *procps_diskstats_select (
if (diskstats_read_failed(info))
return NULL;
if (!(node = node_get(info, name)))
if (!(node = node_get(info, name))) {
errno = ENXIO;
return NULL;
}
diskstats_assign_results(info->select_ext.extents->stacks[0], node);
info->select_ext.dirty_stacks = 1;
@ -963,9 +972,9 @@ PROCPS_EXPORT struct diskstats_stack **procps_diskstats_sort (
struct sort_parms parms;
int offset;
errno = EINVAL;
if (info == NULL || stacks == NULL)
return NULL;
// a diskstats_item is currently unsigned, but we'll protect our future
if (sortitem < 0 || sortitem >= DISKSTATS_logical_end)
return NULL;
@ -984,9 +993,9 @@ PROCPS_EXPORT struct diskstats_stack **procps_diskstats_sort (
return NULL;
++p;
}
parms.offset = offset;
parms.order = order;
errno = 0;
parms.order = order;
qsort_r(stacks, numstacked, sizeof(void *), (QSR_t)Item_table[p->item].sortfunc, &parms);
return stacks;
} // end: procps_diskstats_sort