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SEARCHFS(2) BSD System Calls Manual SEARCHFS(2)
NAME
searchfs -- search a volume quickly
SYNOPSIS
#include <sys/attr.h>
#include <unistd.h>
int
searchfs(const char* path, struct fssearchblock* searchBlock, unsigned int* numMatches,
unsigned int scriptCode, unsigned int options, struct searchstate* state);
DESCRIPTION
The searchfs() function searches the volume (that is, mounted file system) specified by path for file
system objects matching the criteria specified by searchBlock, scriptCode, and options. The numMatches
parameter returns the number of matching file system objects found. The function also returns
attributes of those file system objects in a buffer specified by searchBlock. The searchState parame-ter parameter
ter allows you search the volume using multiple calls to searchfs(), resuming the search where it left
off. The routine will only return objects to which you have access (that is, you have execute permis-sions permissions
sions on the directories leading to this object from the root).
The path parameter must reference a valid file system object on the volume to be searched. Typically
the path is to the volume's root directory. The entire volume is always searched. All directories
listed in the path name leading to this object must be searchable.
The searchBlock parameter is a pointer to an fssearchblock structure, as defined by <sys/attr.h> (shown
below). You are responsible for filling out all fields of this structure before calling the function.
struct fssearchblock {
struct attrlist * returnattrs;
void * returnbuffer;
size_t returnbuffersize;
unsigned int maxmatches;
struct timeval timelimit;
void * searchparams1;
size_t sizeofsearchparams1;
void * searchparams2;
size_t sizeofsearchparams2;
struct attrlist searchattrs;
};
For information about the attrlist structure, see the discussion of getattrlist(2).
The fields of the fssearchblock structure are defined as follows.
returnattrs searchfs() can return arbitrary attributes of the file system objects that meet
the designated search criteria passed in via searchparams1 and searchparams2. This
field must point to an attrlist structure that specifies the attributes that you
want returned. To request an attribute you must set the corresponding bit in the
appropriate attrgroup_t field of the attrlist structure. You are responsible for
filling out all fields of this structure before calling the function. You must
not request volume attributes.
returnbuffer searchfs() places attributes of the matching file system objects into this
returned attributes buffer. The attributes for any given object are grouped
together and packed in exactly the same way as they would be returned from
getdirentriesattr(2). The initial contents of this buffer are ignored.
returnbuffersize Set this field to the size, in bytes, of the buffer pointed to by returnbuffer.
maxmatches Specifies the maximum number of matches that you want this call to searchfs() to
return.
timelimit Specifies the maximum time that you want this call to searchfs() to run.
If you're implementing a volume format, you should impose your own internal limit
on the duration of this call to prevent a malicious user program from monopolizing
kernel resources.
searchparams1 Specifies the lower bound of the search criteria. This is discussed in detail
below. You must place attribute values into the buffer in the same way as they
would be returned by getattrlist(2), where the searchattrs field determines the
exact layout of the attribute values.
sizeofsearchparams1 Set this field to the size, in bytes, of the buffer pointed to by searchparams1.
searchparams2 Specifies the upper bound of the search criteria. This is discussed in detail
below. You must place attribute values into the buffer in the same way as they
would be returned by getattrlist(2), where the searchattrs field determines the
exact layout of the attribute values.
sizeofsearchparams2 Set this field to the size, in bytes, of the buffer pointed to by searchparams2.
searchattrs Specifies the attributes that you want you use for your search criteria. You are
responsible for filling out all fields of this structure before calling the func-tion. function.
tion. To search for an attribute you must set the corresponding bit in the appro-priate appropriate
priate attrgroup_t field of the attrlist structure, and place the appropriate val-ues values
ues into the searchparam1 and searchparam2 buffers. The attributes specified here
determine the format of those buffers. This is discussed in detail below.
The numMatches parameter points to an unsigned int variable. The initial value of this variable is
ignored. On return, this variable contains the number of matching file system objects found. The is
always less than or equal to the maxmatches field of the searchBlock parameter. The attributes for the
matching objects have been placed into the returned attributes buffer.
The scriptCode parameter is currently ignored. You should always pass in the value 0x08000103, which
corresponds to the UTF-8 text encoding value defined by <CarbonCore/TextCommon.h>.
The options parameter is a bit set that controls the behaviour of searchfs(). The following option
bits are defined.
SRCHFS_START If this bit is set, searchfs() will ignore the state parameter and start a
new search. Otherwise searchfs() assumes that searchstate is valid and
attempts to resume a previous search based on that state.
SRCHFS_MATCHPARTIALNAMES If this bit is set, searchfs() will consider substrings to be successful
matches when evaluating the ATTR_CMN_NAME attribute.
SRCHFS_MATCHDIRS If this bit is set, searchfs() will search for directories that match the
search criteria. To get meaningful results you must specify either this bit
or SRCHFS_MATCHFILES, or both.
SRCHFS_MATCHFILES If this bit is set, searchfs() will search for files that match the search
criteria. To get meaningful results you must specify either this bit or
SRCHFS_MATCHDIRS, or both.
SRCHFS_SKIPLINKS If this bit is set, searchfs() will only return one reference for a hard
linked file, rather than a reference for each hard link to the file.
This option is not recommended for general development. Its primary client
is the quotacheck(2) utility. Note that not all filesystems that support
searchfs() support this option and may return EINVAL if it is requested.
This option is privileged (the caller's effective UID must be 0) and cannot
be used if you request the ATTR_CMN_NAME or ATTR_CMN_PAROBJID attributes.
Introduced with Darwin 7.0 (Mac OS X version 10.3).
SRCHFS_SKIPINVISIBLE If this bit is set, searchfs() will not match any invisible file system
objects (that is, objects whose ATTR_CMN_FNDRINFO attribute has bit 6 set in
the ninth byte) or any objects within invisible directories.
Introduced with Darwin 7.0 (Mac OS X version 10.3).
SRCHFS_SKIPPACKAGES If this bit is set, searchfs() will not match any file system objects that
are inside a package. A package is defined as a directory whose extension
matches one of the extensions that are configured into the kernel by Launch
Services.
Introduced with Darwin 7.0 (Mac OS X version 10.3).
SRCHFS_SKIPINAPPROPRIATE If this bit is set, searchfs() will not match any file system objects that
are within an inappropriate directory. The current list of inappropriate
directories contains one item: /System.
Introduced with Darwin 7.0 (Mac OS X version 10.3).
SRCHFS_NEGATEPARAMS If this bit is set, searchfs() will return all the file system objects that
do not match the search criteria.
Introduced with Darwin 7.0 (Mac OS X version 10.3).
The state parameter is a pointer to an opaque data structure that searchfs() uses to maintain the state
of a search between successive calls. In your first call to searchfs(), you specify the SRCHFS_START
flag in the options parameter. This tells searchfs() that the search state is invalid and that it
should start a new search. When this call completes, it may have only returned partial results; in
that case, it will have updated the structure pointed to by state. If you call searchfs() again, this
time without specifying the SRCHFS_START flag in the options parameter, it will resume the search where
it left off, using the search state that it previously stored in the state structure. You do not need
to explicitly dispose of this state.
The searchfs() function returns significant errors in the followings cases.
• If it has found as many objects as you requested in the maxmatches field of the searchBlock parame-ter, parameter,
ter, it will return EAGAIN.
• If there is not enough space in the returned attributes buffer for the first match, it will return
ENOBUFS. You should allocate a larger returned attributes buffer and try again. numMatches will
be zero in this case.
• If the timeout expires it will return EAGAIN.
• If you attempt to resume a search (that is, SRCHFS_START is not specified in the options parameter)
and the catalog has changed since the last search, the function will return EBUSY. You must start
your search again from the beginning.
If searchfs() returns EAGAIN, the value in numMatches may be greater than zero. This is known as a
partial result. You should be sure to process these matches before calling searchfs() again.
SEARCH CRITERIA
You specify the search criteria using a combination of the searchattrs, searchparams1,
sizeofsearchparams1, searchparams2, and sizeofsearchparams2 fields of the searchBlock parameter, and
various flags in the options parameter. The searchattrs field determines the attributes considered
when comparing a file system object to the search criteria. You can specify that an attribute should
be considered by setting the corresponding bit in the appropriate attrgroup_t field of the attrlist
structure. See the discussion of getattrlist(2) for a detailed description of this structure.
The searchparams1, sizeofsearchparams1, searchparams2, and sizeofsearchparams2 fields specify the
attribute values that must be matched. The format of each of these buffers is determined by the
attributes that you're searching for. The values are packed in exactly the same way as they would be
returned from getattrlist(2), including the leading u_int32_t length value. Note that the size of
these buffers must be bounded by SEARCHFS_MAX_SEARCHPARMS bytes, which is defined in <sys/attr.h>.
The attribute values in the first and second search buffers form a lower and upper bound for the
search, respectively. These have different meanings depending on the type of attribute.
• For string attributes (specifically ATTR_CMN_NAME, the object name), the value in the first search
buffer is significant and the value in the second search buffer is ignored. The string comparison
is either an exact match or a substring match depending on the SRCHFS_MATCHPARTIALNAMES flag in the
options parameter.
• For structured attributes (specifically ATTR_CMN_FNDRINFO, the Finder information), the value from
the file system object is masked (logical AND) with the value in the second search buffer and then
compared, byte for byte, against the value in the first search buffer. If it is equal, the object
is a match.
• For scalar attributes (all other attributes, for example, ATTR_CMN_MODTIME, the modification date),
the values in the first and second search buffers are literally a lower and upper bound. An object
matches the criteria if its value is greater than or equal to the value in the first buffer and
less than or equal to the value in the second.
RETURN VALUES
Upon successful completion, a value of 0 is returned. This means that the entire volume has been
searched and all matches returned. Otherwise, a value of -1 is returned and errno is set to indicate
the error.
See the discussion of the EAGAIN, ENOBUFS, and EBUSY error codes above.
COMPATIBILITY
Not all volumes support searchfs(). You can test whether a volume supports searchfs() by using
getattrlist(2) to get the volume capabilities attribute ATTR_VOL_CAPABILITIES, and then testing the
VOL_CAP_INT_SEARCHFS flag.
The searchfs() function has been undocumented for more than two years. In that time a number of volume
format implementations have been created without a proper specification for the behaviour of this rou-tine. routine.
tine. You may encounter volume format implementations with slightly different behaviour than what is
described here. Your program is expected to be tolerant of this variant behaviour.
If you're implementing a volume format that supports searchfs(), you should be careful to support the
behaviour specified by this document.
A bug in systems prior to Darwin 7.0 (Mac OS X version 10.3) makes searching for the ATTR_CMN_BKUPTIME
attribute tricky. The bug causes the attribute to consume two items in the search attribute buffers,
the first in the proper place and the second between ATTR_CMN_FNDRINFO and ATTR_CMN_OWNERID.
ERRORS
searchfs() will fail if:
[ENOTSUP] The volume does not support searchfs().
[ENOTDIR] A component of the path prefix is not a directory.
[ENAMETOOLONG] A component of a path name exceeded NAME_MAX characters, or an entire path name
exceeded PATH_MAX characters.
[ENOENT] The file system object does not exist.
[EACCES] Search permission is denied for a component of the path prefix.
[ELOOP] Too many symbolic links were encountered in translating the pathname.
[EFAULT] One of the pointer parameters points to an invalid address.
[EINVAL] The options parameter contains an invalid flag or sizeofsearchparams1/2 is greater
than SEARCHFS_MAX_SEARCHPARMS (see attr.h). Additionally, filesystems that do not
support SRCHFS_SKIPLINKS may return EINVAL if this search option is requested.
[EAGAIN] The search terminated with partial results, either because numMatches has hit the
limit specified by maxmatches or because the timeout expired. Process the matches
returned so far and then call searchfs() again to look for more.
[ENOBUFS] The returned attributes buffer is too small for the first match. You should allo-cate allocate
cate a larger returned attributes buffer and try again. numMatches will be zero in
this case.
[EBUSY] The search could not be resumed because the volume has changed.
[EIO] An I/O error occurred while reading from or writing to the file system.
CAVEATS
The list of attributes that are valid as search criteria currently includes the following list of
attributes. Note that this list is substantially smaller than what is available via getattrlist(2) for
a particular filesystem object. In general, a filesystem that supports searchfs() will typically sup-ply supply
ply per-item attributes for matched objects that are also supported by the getdirentries(2) system
call. This varies from filesystem to filesystem.
ATTR_CMN_NAME
ATTR_CMN_OBJID
ATTR_CMN_PAROBJID
ATTR_CMN_CRTIME
ATTR_CMN_MODTIME
ATTR_CMN_CHGTIME
ATTR_CMN_ACCTIME
ATTR_CMN_BKUPTIME
ATTR_CMN_FNDRINFO
ATTR_CMN_BKUPTIME
ATTR_CMN_OWNERID
ATTR_CMN_GRPID
ATTR_CMN_ACCESSMASK
ATTR_CMN_FILEID
ATTR_CMN_PARENTID
ATTR_DIR_ENTRYCOUNT
ATTR_FILE_DATALENGTH
ATTR_FILE_DATAALLOCSIZE
ATTR_FILE_RSRCLENGTH
ATTR_FILE_RSRCALLOCSIZE
EXAMPLES
The following code searches a volume for files of the specified type and creator.
#include <assert.h>
#include <stdio.h>
#include <stddef.h>
#include <string.h>
#include <sys/attr.h>
#include <sys/errno.h>
#include <unistd.h>
typedef struct attrlist attrlist_t;
typedef struct fssearchblock fssearchblock_t;
typedef struct searchstate searchstate_t;
struct SearchAttrBuf {
u_int32_t length;
char finderInfo[32];
};
typedef struct SearchAttrBuf SearchAttrBuf;
struct ResultAttrBuf {
u_int32_t length;
attrreference_t name;
fsobj_id_t parObjID;
};
typedef struct ResultAttrBuf ResultAttrBuf;
enum {
kMatchesPerCall = 16
};
static int SearchFSDemo(
const char *volPath,
const char *type,
const char *creator
)
{
int err;
fssearchblock_t searchBlock;
SearchAttrBuf lower;
SearchAttrBuf upper;
static const unsigned char kAllOnes[4] = { 0xFF, 0xFF, 0xFF, 0xFF };
unsigned int matchCount;
unsigned int matchIndex;
unsigned int options;
searchstate_t state;
ResultAttrBuf * thisEntry;
attrlist_t returnAttrList;
char resultAttrBuf[ kMatchesPerCall
* (sizeof(ResultAttrBuf) + 64)];
// resultAttrBuf is big enough for kMatchesPerCall entries,
// assuming that the average name length is less than 64.
assert(strlen(type) == 4);
assert(strlen(creator) == 4);
memset(&searchBlock, 0, sizeof(searchBlock));
searchBlock.searchattrs.bitmapcount = ATTR_BIT_MAP_COUNT;
searchBlock.searchattrs.commonattr = ATTR_CMN_FNDRINFO;
memset(&lower, 0, sizeof(lower));
memset(&upper, 0, sizeof(upper));
lower.length = sizeof(lower);
upper.length = sizeof(upper);
memcpy(&lower.finderInfo[0], type, 4);
memcpy(&lower.finderInfo[4], creator, 4);
memcpy(&upper.finderInfo[0], kAllOnes, 4);
memcpy(&upper.finderInfo[4], kAllOnes, 4);
searchBlock.searchparams1 = &lower;
searchBlock.sizeofsearchparams1 = sizeof(lower);
searchBlock.searchparams2 = &upper;
searchBlock.sizeofsearchparams2 = sizeof(lower);
searchBlock.timelimit.tv_sec = 0;
searchBlock.timelimit.tv_usec = 100 * 1000;
searchBlock.maxmatches = kMatchesPerCall;
memset(&returnAttrList, 0, sizeof(returnAttrList));
returnAttrList.bitmapcount = ATTR_BIT_MAP_COUNT;
returnAttrList.commonattr = ATTR_CMN_NAME | ATTR_CMN_PAROBJID;
searchBlock.returnattrs = &returnAttrList;
searchBlock.returnbuffer = resultAttrBuf;
searchBlock.returnbuffersize = sizeof(resultAttrBuf);
options = SRCHFS_START | SRCHFS_MATCHFILES;
do {
err = searchfs(
volPath,
&searchBlock,
&matchCount,
0x08000103,
options,
&state
);
if (err != 0) {
err = errno;
}
if ( (err == 0) || (err == EAGAIN) ) {
thisEntry = (ResultAttrBuf *) resultAttrBuf;
for (matchIndex = 0; matchIndex < matchCount; matchIndex++) {
printf("%08x ", thisEntry->parObjID.fid_objno);
printf(
"%s\n",
((char *) &thisEntry->name)
+ thisEntry->name.attr_dataoffset
);
// Advance to the next entry.
((char *) thisEntry) += thisEntry->length;
}
}
options &= ~SRCHFS_START;
} while (err == EAGAIN);
return err;
}
SEE ALSO
getattrlist(2)
HISTORY
A searchfs() function call appeared in Darwin 1.3.1 (Mac OS X version 10.0).
Darwin October 13, 2008 Darwin
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