--- src/secure/lib/libcrypto/man/lhash.3 2004/09/02 09:26:58 1.2 +++ src/secure/lib/libcrypto/man/lhash.3 2004/12/18 21:34:10 1.3 @@ -1,12 +1,8 @@ -.rn '' }` -''' $RCSfile: lhash.3,v $$Revision: 1.2 $$Date: 2004/09/02 09:26:58 $ -''' -''' $Log: lhash.3,v $ -''' Revision 1.2 2004/09/02 09:26:58 asmodai -''' Commit manual pages after running 'man-update' and add new manual pages. -''' -''' -.de Sh +.\" Automatically generated by Pod::Man v1.37, Pod::Parser v1.14 +.\" +.\" Standard preamble: +.\" ======================================================================== +.de Sh \" Subsection heading .br .if t .Sp .ne 5 @@ -14,150 +10,98 @@ \fB\\$1\fR .PP .. -.de Sp +.de Sp \" Vertical space (when we can't use .PP) .if t .sp .5v .if n .sp .. -.de Ip -.br -.ie \\n(.$>=3 .ne \\$3 -.el .ne 3 -.IP "\\$1" \\$2 -.. -.de Vb +.de Vb \" Begin verbatim text .ft CW .nf .ne \\$1 .. -.de Ve +.de Ve \" End verbatim text .ft R - .fi .. -''' -''' -''' Set up \*(-- to give an unbreakable dash; -''' string Tr holds user defined translation string. -''' Bell System Logo is used as a dummy character. -''' +.\" Set up some character translations and predefined strings. \*(-- will +.\" give an unbreakable dash, \*(PI will give pi, \*(L" will give a left +.\" double quote, and \*(R" will give a right double quote. | will give a +.\" real vertical bar. \*(C+ will give a nicer C++. Capital omega is used to +.\" do unbreakable dashes and therefore won't be available. \*(C` and \*(C' +.\" expand to `' in nroff, nothing in troff, for use with C<>. .tr \(*W-|\(bv\*(Tr +.ds C+ C\v'-.1v'\h'-1p'\s-2+\h'-1p'+\s0\v'.1v'\h'-1p' .ie n \{\ -.ds -- \(*W- -.ds PI pi -.if (\n(.H=4u)&(1m=24u) .ds -- \(*W\h'-12u'\(*W\h'-12u'-\" diablo 10 pitch -.if (\n(.H=4u)&(1m=20u) .ds -- \(*W\h'-12u'\(*W\h'-8u'-\" diablo 12 pitch -.ds L" "" -.ds R" "" -''' \*(M", \*(S", \*(N" and \*(T" are the equivalent of -''' \*(L" and \*(R", except that they are used on ".xx" lines, -''' such as .IP and .SH, which do another additional levels of -''' double-quote interpretation -.ds M" """ -.ds S" """ -.ds N" """"" -.ds T" """"" -.ds L' ' -.ds R' ' -.ds M' ' -.ds S' ' -.ds N' ' -.ds T' ' +. ds -- \(*W- +. ds PI pi +. if (\n(.H=4u)&(1m=24u) .ds -- \(*W\h'-12u'\(*W\h'-12u'-\" diablo 10 pitch +. if (\n(.H=4u)&(1m=20u) .ds -- \(*W\h'-12u'\(*W\h'-8u'-\" diablo 12 pitch +. ds L" "" +. ds R" "" +. ds C` "" +. ds C' "" 'br\} .el\{\ -.ds -- \(em\| -.tr \*(Tr -.ds L" `` -.ds R" '' -.ds M" `` -.ds S" '' -.ds N" `` -.ds T" '' -.ds L' ` -.ds R' ' -.ds M' ` -.ds S' ' -.ds N' ` -.ds T' ' -.ds PI \(*p +. ds -- \|\(em\| +. ds PI \(*p +. ds L" `` +. ds R" '' 'br\} -.\" If the F register is turned on, we'll generate -.\" index entries out stderr for the following things: -.\" TH Title -.\" SH Header -.\" Sh Subsection -.\" Ip Item -.\" X<> Xref (embedded -.\" Of course, you have to process the output yourself -.\" in some meaninful fashion. -.if \nF \{ -.de IX -.tm Index:\\$1\t\\n%\t"\\$2" +.\" +.\" If the F register is turned on, we'll generate index entries on stderr for +.\" titles (.TH), headers (.SH), subsections (.Sh), items (.Ip), and index +.\" entries marked with X<> in POD. Of course, you'll have to process the +.\" output yourself in some meaningful fashion. +.if \nF \{\ +. de IX +. tm Index:\\$1\t\\n%\t"\\$2" .. -.nr % 0 -.rr F +. nr % 0 +. rr F .\} -.TH lhash 3 "0.9.7d" "2/Sep/2004" "OpenSSL" -.UC -.if n .hy 0 +.\" +.\" For nroff, turn off justification. Always turn off hyphenation; it makes +.\" way too many mistakes in technical documents. +.hy 0 .if n .na -.ds C+ C\v'-.1v'\h'-1p'\s-2+\h'-1p'+\s0\v'.1v'\h'-1p' -.de CQ \" put $1 in typewriter font -.ft CW -'if n "\c -'if t \\&\\$1\c -'if n \\&\\$1\c -'if n \&" -\\&\\$2 \\$3 \\$4 \\$5 \\$6 \\$7 -'.ft R -.. -.\" @(#)ms.acc 1.5 88/02/08 SMI; from UCB 4.2 -. \" AM - accent mark definitions -.bd B 3 -. \" fudge factors for nroff and troff +.\" +.\" Accent mark definitions (@(#)ms.acc 1.5 88/02/08 SMI; from UCB 4.2). +.\" Fear. Run. Save yourself. No user-serviceable parts. +. \" fudge factors for nroff and troff .if n \{\ -. ds #H 0 -. ds #V .8m -. ds #F .3m -. ds #[ \f1 -. ds #] \fP +. ds #H 0 +. ds #V .8m +. ds #F .3m +. ds #[ \f1 +. ds #] \fP .\} .if t \{\ -. ds #H ((1u-(\\\\n(.fu%2u))*.13m) -. ds #V .6m -. ds #F 0 -. ds #[ \& -. ds #] \& +. ds #H ((1u-(\\\\n(.fu%2u))*.13m) +. ds #V .6m +. ds #F 0 +. ds #[ \& +. ds #] \& .\} -. \" simple accents for nroff and troff +. \" simple accents for nroff and troff .if n \{\ -. ds ' \& -. ds ` \& -. ds ^ \& -. ds , \& -. ds ~ ~ -. ds ? ? -. ds ! ! -. ds / -. ds q +. ds ' \& +. ds ` \& +. ds ^ \& +. ds , \& +. ds ~ ~ +. ds / .\} .if t \{\ -. ds ' \\k:\h'-(\\n(.wu*8/10-\*(#H)'\'\h"|\\n:u" -. ds ` \\k:\h'-(\\n(.wu*8/10-\*(#H)'\`\h'|\\n:u' -. ds ^ \\k:\h'-(\\n(.wu*10/11-\*(#H)'^\h'|\\n:u' -. ds , \\k:\h'-(\\n(.wu*8/10)',\h'|\\n:u' -. ds ~ \\k:\h'-(\\n(.wu-\*(#H-.1m)'~\h'|\\n:u' -. ds ? \s-2c\h'-\w'c'u*7/10'\u\h'\*(#H'\zi\d\s+2\h'\w'c'u*8/10' -. ds ! \s-2\(or\s+2\h'-\w'\(or'u'\v'-.8m'.\v'.8m' -. ds / \\k:\h'-(\\n(.wu*8/10-\*(#H)'\z\(sl\h'|\\n:u' -. ds q o\h'-\w'o'u*8/10'\s-4\v'.4m'\z\(*i\v'-.4m'\s+4\h'\w'o'u*8/10' +. ds ' \\k:\h'-(\\n(.wu*8/10-\*(#H)'\'\h"|\\n:u" +. ds ` \\k:\h'-(\\n(.wu*8/10-\*(#H)'\`\h'|\\n:u' +. ds ^ \\k:\h'-(\\n(.wu*10/11-\*(#H)'^\h'|\\n:u' +. ds , \\k:\h'-(\\n(.wu*8/10)',\h'|\\n:u' +. ds ~ \\k:\h'-(\\n(.wu-\*(#H-.1m)'~\h'|\\n:u' +. ds / \\k:\h'-(\\n(.wu*8/10-\*(#H)'\z\(sl\h'|\\n:u' .\} -. \" troff and (daisy-wheel) nroff accents +. \" troff and (daisy-wheel) nroff accents .ds : \\k:\h'-(\\n(.wu*8/10-\*(#H+.1m+\*(#F)'\v'-\*(#V'\z.\h'.2m+\*(#F'.\h'|\\n:u'\v'\*(#V' .ds 8 \h'\*(#H'\(*b\h'-\*(#H' -.ds v \\k:\h'-(\\n(.wu*9/10-\*(#H)'\v'-\*(#V'\*(#[\s-4v\s0\v'\*(#V'\h'|\\n:u'\*(#] -.ds _ \\k:\h'-(\\n(.wu*9/10-\*(#H+(\*(#F*2/3))'\v'-.4m'\z\(hy\v'.4m'\h'|\\n:u' -.ds . \\k:\h'-(\\n(.wu*8/10)'\v'\*(#V*4/10'\z.\v'-\*(#V*4/10'\h'|\\n:u' -.ds 3 \*(#[\v'.2m'\s-2\&3\s0\v'-.2m'\*(#] .ds o \\k:\h'-(\\n(.wu+\w'\(de'u-\*(#H)/2u'\v'-.3n'\*(#[\z\(de\v'.3n'\h'|\\n:u'\*(#] .ds d- \h'\*(#H'\(pd\h'-\w'~'u'\v'-.25m'\f2\(hy\fP\v'.25m'\h'-\*(#H' .ds D- D\\k:\h'-\w'D'u'\v'-.11m'\z\(hy\v'.11m'\h'|\\n:u' @@ -165,55 +109,56 @@ .ds Th \*(#[\s+2I\s-2\h'-\w'I'u*3/5'\v'-.3m'o\v'.3m'\*(#] .ds ae a\h'-(\w'a'u*4/10)'e .ds Ae A\h'-(\w'A'u*4/10)'E -.ds oe o\h'-(\w'o'u*4/10)'e -.ds Oe O\h'-(\w'O'u*4/10)'E -. \" corrections for vroff +. \" corrections for vroff .if v .ds ~ \\k:\h'-(\\n(.wu*9/10-\*(#H)'\s-2\u~\d\s+2\h'|\\n:u' .if v .ds ^ \\k:\h'-(\\n(.wu*10/11-\*(#H)'\v'-.4m'^\v'.4m'\h'|\\n:u' -. \" for low resolution devices (crt and lpr) +. \" for low resolution devices (crt and lpr) .if \n(.H>23 .if \n(.V>19 \ \{\ -. ds : e -. ds 8 ss -. ds v \h'-1'\o'\(aa\(ga' -. ds _ \h'-1'^ -. ds . \h'-1'. -. ds 3 3 -. ds o a -. ds d- d\h'-1'\(ga -. ds D- D\h'-1'\(hy -. ds th \o'bp' -. ds Th \o'LP' -. ds ae ae -. ds Ae AE -. ds oe oe -. ds Oe OE +. ds : e +. ds 8 ss +. ds o a +. ds d- d\h'-1'\(ga +. ds D- D\h'-1'\(hy +. ds th \o'bp' +. ds Th \o'LP' +. ds ae ae +. ds Ae AE .\} .rm #[ #] #H #V #F C +.\" ======================================================================== +.\" +.IX Title "lhash 3" +.TH lhash 3 "2004-12-18" "0.9.7e" "OpenSSL" .SH "NAME" lh_new, lh_free, lh_insert, lh_delete, lh_retrieve, lh_doall, lh_doall_arg, lh_error \- dynamic hash table .SH "SYNOPSIS" -.PP +.IX Header "SYNOPSIS" .Vb 1 \& #include .Ve +.PP .Vb 2 \& LHASH *lh_new(LHASH_HASH_FN_TYPE hash, LHASH_COMP_FN_TYPE compare); \& void lh_free(LHASH *table); .Ve +.PP .Vb 3 \& void *lh_insert(LHASH *table, void *data); \& void *lh_delete(LHASH *table, void *data); \& void *lh_retrieve(LHASH *table, void *data); .Ve +.PP .Vb 3 \& void lh_doall(LHASH *table, LHASH_DOALL_FN_TYPE func); \& void lh_doall_arg(LHASH *table, LHASH_DOALL_ARG_FN_TYPE func, \& void *arg); .Ve +.PP .Vb 1 \& int lh_error(LHASH *table); .Ve +.PP .Vb 4 \& typedef int (*LHASH_COMP_FN_TYPE)(const void *, const void *); \& typedef unsigned long (*LHASH_HASH_FN_TYPE)(const void *); @@ -221,12 +166,13 @@ lh_new, lh_free, lh_insert, lh_delete, l \& typedef void (*LHASH_DOALL_ARG_FN_TYPE)(const void *, const void *); .Ve .SH "DESCRIPTION" +.IX Header "DESCRIPTION" This library implements dynamic hash tables. The hash table entries can be arbitrary structures. Usually they consist of key and value fields. .PP -\fIlh_new()\fR creates a new \fBLHASH\fR structure to store arbitrary data -entries, and provides the \*(L'hash\*(R' and \*(L'compare\*(R' callbacks to be used in +\&\fIlh_new()\fR creates a new \fB\s-1LHASH\s0\fR structure to store arbitrary data +entries, and provides the 'hash' and 'compare' callbacks to be used in organising the table's entries. The \fBhash\fR callback takes a pointer to a table entry as its argument and returns an unsigned long hash value for its key field. The hash value is normally truncated to a @@ -235,8 +181,8 @@ low order bits. The \fBcompare\fR callb to two hash table entries), and returns 0 if their keys are equal, non-zero otherwise. If your hash table will contain items of some particular type and the \fBhash\fR and \fBcompare\fR callbacks hash/compare -these types, then the \fBDECLARE_LHASH_HASH_FN\fR and -\fBIMPLEMENT_LHASH_COMP_FN\fR macros can be used to create callback +these types, then the \fB\s-1DECLARE_LHASH_HASH_FN\s0\fR and +\&\fB\s-1IMPLEMENT_LHASH_COMP_FN\s0\fR macros can be used to create callback wrappers of the prototypes required by \fIlh_new()\fR. These provide per-variable casts before calling the type-specific callbacks written by the application author. These macros, as well as those used for @@ -251,6 +197,7 @@ the \*(L"doall\*(R" callbacks, are defin \& return f_name(a); } \& #define LHASH_HASH_FN(f_name) f_name##_LHASH_HASH .Ve +.PP .Vb 8 \& #define DECLARE_LHASH_COMP_FN(f_name,o_type) \e \& int f_name##_LHASH_COMP(const void *, const void *); @@ -261,6 +208,7 @@ the \*(L"doall\*(R" callbacks, are defin \& return f_name(a,b); } \& #define LHASH_COMP_FN(f_name) f_name##_LHASH_COMP .Ve +.PP .Vb 7 \& #define DECLARE_LHASH_DOALL_FN(f_name,o_type) \e \& void f_name##_LHASH_DOALL(const void *); @@ -270,6 +218,7 @@ the \*(L"doall\*(R" callbacks, are defin \& f_name(a); } \& #define LHASH_DOALL_FN(f_name) f_name##_LHASH_DOALL .Ve +.PP .Vb 8 \& #define DECLARE_LHASH_DOALL_ARG_FN(f_name,o_type,a_type) \e \& void f_name##_LHASH_DOALL_ARG(const void *, const void *); @@ -280,7 +229,8 @@ the \*(L"doall\*(R" callbacks, are defin \& f_name(a,b); } \& #define LHASH_DOALL_ARG_FN(f_name) f_name##_LHASH_DOALL_ARG .Ve -An example of a hash table storing (pointers to) structures of type \*(L'STUFF\*(R' +.PP +An example of a hash table storing (pointers to) structures of type '\s-1STUFF\s0' could be defined as follows; .PP .Vb 14 @@ -299,25 +249,26 @@ could be defined as follows; \& /* ... */ \& } .Ve -\fIlh_free()\fR frees the \fBLHASH\fR structure \fBtable\fR. Allocated hash table +.PP +\&\fIlh_free()\fR frees the \fB\s-1LHASH\s0\fR structure \fBtable\fR. Allocated hash table entries will not be freed; consider using \fIlh_doall()\fR to deallocate any remaining entries in the hash table (see below). .PP -\fIlh_insert()\fR inserts the structure pointed to by \fBdata\fR into \fBtable\fR. +\&\fIlh_insert()\fR inserts the structure pointed to by \fBdata\fR into \fBtable\fR. If there already is an entry with the same key, the old value is replaced. Note that \fIlh_insert()\fR stores pointers, the data are not copied. .PP -\fIlh_delete()\fR deletes an entry from \fBtable\fR. +\&\fIlh_delete()\fR deletes an entry from \fBtable\fR. .PP -\fIlh_retrieve()\fR looks up an entry in \fBtable\fR. Normally, \fBdata\fR is -a structure with the key \fIfield\fR\|(s) set; the function will return a +\&\fIlh_retrieve()\fR looks up an entry in \fBtable\fR. Normally, \fBdata\fR is +a structure with the key field(s) set; the function will return a pointer to a fully populated structure. .PP -\fIlh_doall()\fR will, for every entry in the hash table, call \fBfunc\fR with +\&\fIlh_doall()\fR will, for every entry in the hash table, call \fBfunc\fR with the data item as its parameter. For \fIlh_doall()\fR and \fIlh_doall_arg()\fR, function pointer casting should be avoided in the callbacks (see -\fBNOTE\fR) \- instead, either declare the callbacks to match the +\&\fB\s-1NOTE\s0\fR) \- instead, either declare the callbacks to match the prototype required in \fIlh_new()\fR or use the declare/implement macros to create type-safe wrappers that cast variables prior to calling your type-specific callbacks. An example of this is illustrated here where @@ -335,27 +286,28 @@ prior to the hashtable itself being deal \& /* Then the hash table itself can be deallocated */ \& lh_free(hashtable); .Ve +.PP When doing this, be careful if you delete entries from the hash table in your callbacks: the table may decrease in size, moving the item that you are currently on down lower in the hash table \- this could cause some entries to be skipped during the iteration. The second -best solution to this problem is to set hash->down_load=0 before +best solution to this problem is to set hash\->down_load=0 before you start (which will stop the hash table ever decreasing in size). The best solution is probably to avoid deleting items from the hash table inside a \*(L"doall\*(R" callback! .PP -\fIlh_doall_arg()\fR is the same as \fIlh_doall()\fR except that \fBfunc\fR will be +\&\fIlh_doall_arg()\fR is the same as \fIlh_doall()\fR except that \fBfunc\fR will be called with \fBarg\fR as the second argument and \fBfunc\fR should be of -type \fBLHASH_DOALL_ARG_FN_TYPE\fR (a callback prototype that is passed +type \fB\s-1LHASH_DOALL_ARG_FN_TYPE\s0\fR (a callback prototype that is passed both the table entry and an extra argument). As with \fIlh_doall()\fR, you can instead choose to declare your callback with a prototype matching the types you are dealing with and use the declare/implement macros to create compatible wrappers that cast variables before calling your type-specific callbacks. An example of this is demonstrated here -(printing all hash table entries to a BIO that is provided by the +(printing all hash table entries to a \s-1BIO\s0 that is provided by the caller): .PP -.Vb 10 +.Vb 7 \& /* Prints item 'a' to 'output_bio' (this is implemented elsewhere) */ \& void STUFF_print(const STUFF *a, BIO *output_bio); \& /* Implement a prototype-compatible wrapper for "STUFF_print" */ @@ -363,143 +315,127 @@ caller): \& /* ... then later in the code ... */ \& /* Print out the entire hashtable to a particular BIO */ \& lh_doall_arg(hashtable, LHASH_DOALL_ARG_FN(STUFF_print), logging_bio); -\& -\&lh_error() can be used to determine if an error occurred in the last -\&operation. lh_error() is a macro. .Ve +.PP +\&\fIlh_error()\fR can be used to determine if an error occurred in the last +operation. \fIlh_error()\fR is a macro. .SH "RETURN VALUES" -\fIlh_new()\fR returns \fBNULL\fR on error, otherwise a pointer to the new -\fBLHASH\fR structure. +.IX Header "RETURN VALUES" +\&\fIlh_new()\fR returns \fB\s-1NULL\s0\fR on error, otherwise a pointer to the new +\&\fB\s-1LHASH\s0\fR structure. .PP When a hash table entry is replaced, \fIlh_insert()\fR returns the value -being replaced. \fBNULL\fR is returned on normal operation and on error. +being replaced. \fB\s-1NULL\s0\fR is returned on normal operation and on error. .PP -\fIlh_delete()\fR returns the entry being deleted. \fBNULL\fR is returned if +\&\fIlh_delete()\fR returns the entry being deleted. \fB\s-1NULL\s0\fR is returned if there is no such value in the hash table. .PP -\fIlh_retrieve()\fR returns the hash table entry if it has been found, -\fBNULL\fR otherwise. +\&\fIlh_retrieve()\fR returns the hash table entry if it has been found, +\&\fB\s-1NULL\s0\fR otherwise. .PP -\fIlh_error()\fR returns 1 if an error occurred in the last operation, 0 +\&\fIlh_error()\fR returns 1 if an error occurred in the last operation, 0 otherwise. .PP -\fIlh_free()\fR, \fIlh_doall()\fR and \fIlh_doall_arg()\fR return no values. +\&\fIlh_free()\fR, \fIlh_doall()\fR and \fIlh_doall_arg()\fR return no values. .SH "NOTE" -The various LHASH macros and callback types exist to make it possible +.IX Header "NOTE" +The various \s-1LHASH\s0 macros and callback types exist to make it possible to write type-safe code without resorting to function-prototype casting \- an evil that makes application code much harder to audit/verify and also opens the window of opportunity for stack corruption and other hard-to-find bugs. It also, apparently, violates -ANSI\-C. +\&\s-1ANSI\-C\s0. .PP -The LHASH code regards table entries as constant data. As such, it +The \s-1LHASH\s0 code regards table entries as constant data. As such, it internally represents \fIlh_insert()\fR'd items with a \*(L"const void *\*(R" pointer type. This is why callbacks such as those used by \fIlh_doall()\fR and \fIlh_doall_arg()\fR declare their prototypes with \*(L"const\*(R", even for the -parameters that pass back the table items\*(R' data pointers \- for +parameters that pass back the table items' data pointers \- for consistency, user-provided data is \*(L"const\*(R" at all times as far as the -LHASH code is concerned. However, as callers are themselves providing +\&\s-1LHASH\s0 code is concerned. However, as callers are themselves providing these pointers, they can choose whether they too should be treating all such parameters as constant. .PP As an example, a hash table may be maintained by code that, for reasons of encapsulation, has only \*(L"const\*(R" access to the data being indexed in the hash table (ie. it is returned as \*(L"const\*(R" from -elsewhere in their code) \- in this case the LHASH prototypes are -appropriate as-is. Conversely, if the caller is responsible for the +elsewhere in their code) \- in this case the \s-1LHASH\s0 prototypes are +appropriate as\-is. Conversely, if the caller is responsible for the life-time of the data in question, then they may well wish to make modifications to table item passed back in the \fIlh_doall()\fR or -\fIlh_doall_arg()\fR callbacks (see the \*(L"STUFF_cleanup\*(R" example above). If +\&\fIlh_doall_arg()\fR callbacks (see the \*(L"STUFF_cleanup\*(R" example above). If so, the caller can either cast the \*(L"const\*(R" away (if they're providing the raw callbacks themselves) or use the macros to declare/implement the wrapper functions without \*(L"const\*(R" types. .PP Callers that only have \*(L"const\*(R" access to data they're indexing in a table, yet declare callbacks without constant types (or cast the -\*(L"const\*(R" away themselves), are therefore creating their own risks/bugs -without being encouraged to do so by the API. On a related note, +\&\*(L"const\*(R" away themselves), are therefore creating their own risks/bugs +without being encouraged to do so by the \s-1API\s0. On a related note, those auditing code should pay special attention to any instances of -DECLARE/IMPLEMENT_LHASH_DOALL_[ARG_]_FN macros that provide types +DECLARE/IMPLEMENT_LHASH_DOALL_[\s-1ARG_\s0]_FN macros that provide types without any \*(L"const\*(R" qualifiers. .SH "BUGS" -\fIlh_insert()\fR returns \fBNULL\fR both for success and error. +.IX Header "BUGS" +\&\fIlh_insert()\fR returns \fB\s-1NULL\s0\fR both for success and error. .SH "INTERNALS" +.IX Header "INTERNALS" The following description is based on the SSLeay documentation: .PP The \fBlhash\fR library implements a hash table described in the -\fICommunications of the ACM\fR in 1991. What makes this hash table +\&\fICommunications of the \s-1ACM\s0\fR in 1991. What makes this hash table different is that as the table fills, the hash table is increased (or -decreased) in size via \fIOPENSSL_realloc()\fR. When a \*(L'resize\*(R' is done, instead of -all hashes being redistributed over twice as many \*(L'buckets\*(R', one -bucket is split. So when an \*(L'expand\*(R' is done, there is only a minimal +decreased) in size via \fIOPENSSL_realloc()\fR. When a 'resize' is done, instead of +all hashes being redistributed over twice as many 'buckets', one +bucket is split. So when an 'expand' is done, there is only a minimal cost to redistribute some values. Subsequent inserts will cause more -single \*(L'bucket\*(R' redistributions but there will never be a sudden large -cost due to redistributing all the \*(L'buckets\*(R'. +single 'bucket' redistributions but there will never be a sudden large +cost due to redistributing all the 'buckets'. .PP -The state for a particular hash table is kept in the \fBLHASH\fR structure. +The state for a particular hash table is kept in the \fB\s-1LHASH\s0\fR structure. The decision to increase or decrease the hash table size is made -depending on the \*(L'load\*(R' of the hash table. The load is the number of +depending on the 'load' of the hash table. The load is the number of items in the hash table divided by the size of the hash table. The -default values are as follows. If (hash->up_load < load) => -expand. if (hash->down_load > load) => contract. The -\fBup_load\fR has a default value of 1 and \fBdown_load\fR has a default value +default values are as follows. If (hash\->up_load < load) => +expand. if (hash\->down_load > load) => contract. The +\&\fBup_load\fR has a default value of 1 and \fBdown_load\fR has a default value of 2. These numbers can be modified by the application by just -playing with the \fBup_load\fR and \fBdown_load\fR variables. The \*(L'load\*(R' is +playing with the \fBup_load\fR and \fBdown_load\fR variables. The 'load' is kept in a form which is multiplied by 256. So -hash->up_load=8*256; will cause a load of 8 to be set. +hash\->up_load=8*256; will cause a load of 8 to be set. .PP If you are interested in performance the field to watch is -num_comp_calls. The hash library keeps track of the \*(L'hash\*(R' value for -each item so when a lookup is done, the \*(L'hashes\*(R' are compared, if +num_comp_calls. The hash library keeps track of the 'hash' value for +each item so when a lookup is done, the 'hashes' are compared, if there is a match, then a full compare is done, and -hash->num_comp_calls is incremented. If num_comp_calls is not equal +hash\->num_comp_calls is incremented. If num_comp_calls is not equal to num_delete plus num_retrieve it means that your hash function is generating hashes that are the same for different values. It is probably worth changing your hash function if this is the case because -even if your hash table has 10 items in a \*(L'bucket\*(R', it can be searched +even if your hash table has 10 items in a 'bucket', it can be searched with 10 \fBunsigned long\fR compares and 10 linked list traverses. This will be much less expensive that 10 calls to your compare function. .PP -\fIlh_strhash()\fR is a demo string hashing function: +\&\fIlh_strhash()\fR is a demo string hashing function: .PP .Vb 1 \& unsigned long lh_strhash(const char *c); .Ve -Since the \fBLHASH\fR routines would normally be passed structures, this +.PP +Since the \fB\s-1LHASH\s0\fR routines would normally be passed structures, this routine would not normally be passed to \fIlh_new()\fR, rather it would be used in the function passed to \fIlh_new()\fR. .SH "SEE ALSO" -lh_stats(3) +.IX Header "SEE ALSO" +\&\fIlh_stats\fR\|(3) .SH "HISTORY" +.IX Header "HISTORY" The \fBlhash\fR library is available in all versions of SSLeay and OpenSSL. -\fIlh_error()\fR was added in SSLeay 0.9.1b. +\&\fIlh_error()\fR was added in SSLeay 0.9.1b. .PP This manpage is derived from the SSLeay documentation. .PP In OpenSSL 0.9.7, all lhash functions that were passed function pointers -were changed for better type safety, and the function types LHASH_COMP_FN_TYPE, -LHASH_HASH_FN_TYPE, LHASH_DOALL_FN_TYPE and LHASH_DOALL_ARG_FN_TYPE +were changed for better type safety, and the function types \s-1LHASH_COMP_FN_TYPE\s0, +\&\s-1LHASH_HASH_FN_TYPE\s0, \s-1LHASH_DOALL_FN_TYPE\s0 and \s-1LHASH_DOALL_ARG_FN_TYPE\s0 became available. - -.rn }` '' -.IX Title "lhash 3" -.IX Name "lh_new, lh_free, lh_insert, lh_delete, lh_retrieve, lh_doall, lh_doall_arg, lh_error - dynamic hash table" - -.IX Header "NAME" - -.IX Header "SYNOPSIS" - -.IX Header "DESCRIPTION" - -.IX Header "RETURN VALUES" - -.IX Header "NOTE" - -.IX Header "BUGS" - -.IX Header "INTERNALS" - -.IX Header "SEE ALSO" - -.IX Header "HISTORY" -