1 llvm-ar - LLVM archiver 2 ======================= 3 4 5 SYNOPSIS 6 -------- 7 8 9 **llvm-ar** [-]{dmpqrtx}[Rabfikou] [relpos] [count] <archive> [files...] 10 11 12 DESCRIPTION 13 ----------- 14 15 16 The **llvm-ar** command is similar to the common Unix utility, ``ar``. It 17 archives several files together into a single file. The intent for this is 18 to produce archive libraries by LLVM bitcode that can be linked into an 19 LLVM program. However, the archive can contain any kind of file. By default, 20 **llvm-ar** generates a symbol table that makes linking faster because 21 only the symbol table needs to be consulted, not each individual file member 22 of the archive. 23 24 The **llvm-ar** command can be used to *read* SVR4, GNU and BSD style archive 25 files. However, right now it can only write in the GNU format. If an 26 SVR4 or BSD style archive is used with the ``r`` (replace) or ``q`` (quick 27 update) operations, the archive will be reconstructed in GNU format. 28 29 Here's where **llvm-ar** departs from previous ``ar`` implementations: 30 31 32 *Symbol Table* 33 34 Since **llvm-ar** supports bitcode files. The symbol table it creates 35 is in GNU format and includes both native and bitcode files. 36 37 38 *Long Paths* 39 40 Currently **llvm-ar** can read GNU and BSD long file names, but only writes 41 archives with the GNU format. 42 43 44 45 OPTIONS 46 ------- 47 48 49 The options to **llvm-ar** are compatible with other ``ar`` implementations. 50 However, there are a few modifiers (*R*) that are not found in other ``ar`` 51 implementations. The options to **llvm-ar** specify a single basic operation to 52 perform on the archive, a variety of modifiers for that operation, the name of 53 the archive file, and an optional list of file names. These options are used to 54 determine how **llvm-ar** should process the archive file. 55 56 The Operations and Modifiers are explained in the sections below. The minimal 57 set of options is at least one operator and the name of the archive. Typically 58 archive files end with a ``.a`` suffix, but this is not required. Following 59 the *archive-name* comes a list of *files* that indicate the specific members 60 of the archive to operate on. If the *files* option is not specified, it 61 generally means either "none" or "all" members, depending on the operation. 62 63 Operations 64 ~~~~~~~~~~ 65 66 67 68 d 69 70 Delete files from the archive. No modifiers are applicable to this operation. 71 The *files* options specify which members should be removed from the 72 archive. It is not an error if a specified file does not appear in the archive. 73 If no *files* are specified, the archive is not modified. 74 75 76 77 m[abi] 78 79 Move files from one location in the archive to another. The *a*, *b*, and 80 *i* modifiers apply to this operation. The *files* will all be moved 81 to the location given by the modifiers. If no modifiers are used, the files 82 will be moved to the end of the archive. If no *files* are specified, the 83 archive is not modified. 84 85 86 87 p 88 89 Print files to the standard output. This operation simply prints the 90 *files* indicated to the standard output. If no *files* are 91 specified, the entire archive is printed. Printing bitcode files is 92 ill-advised as they might confuse your terminal settings. The *p* 93 operation never modifies the archive. 94 95 96 97 q 98 99 Quickly append files to the end of the archive. This operation quickly adds the 100 *files* to the archive without checking for duplicates that should be 101 removed first. If no *files* are specified, the archive is not modified. 102 Because of the way that **llvm-ar** constructs the archive file, its dubious 103 whether the *q* operation is any faster than the *r* operation. 104 105 106 107 r[abu] 108 109 Replace or insert file members. The *a*, *b*, and *u* 110 modifiers apply to this operation. This operation will replace existing 111 *files* or insert them at the end of the archive if they do not exist. If no 112 *files* are specified, the archive is not modified. 113 114 115 116 t[v] 117 118 Print the table of contents. Without any modifiers, this operation just prints 119 the names of the members to the standard output. With the *v* modifier, 120 **llvm-ar** also prints out the file type (B=bitcode, S=symbol 121 table, blank=regular file), the permission mode, the owner and group, the 122 size, and the date. If any *files* are specified, the listing is only for 123 those files. If no *files* are specified, the table of contents for the 124 whole archive is printed. 125 126 127 128 x[oP] 129 130 Extract archive members back to files. The *o* modifier applies to this 131 operation. This operation retrieves the indicated *files* from the archive 132 and writes them back to the operating system's file system. If no 133 *files* are specified, the entire archive is extract. 134 135 136 137 138 Modifiers (operation specific) 139 ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~ 140 141 142 The modifiers below are specific to certain operations. See the Operations 143 section (above) to determine which modifiers are applicable to which operations. 144 145 146 [a] 147 148 When inserting or moving member files, this option specifies the destination of 149 the new files as being after the *relpos* member. If *relpos* is not found, 150 the files are placed at the end of the archive. 151 152 153 154 [b] 155 156 When inserting or moving member files, this option specifies the destination of 157 the new files as being before the *relpos* member. If *relpos* is not 158 found, the files are placed at the end of the archive. This modifier is 159 identical to the *i* modifier. 160 161 162 163 [i] 164 165 A synonym for the *b* option. 166 167 168 169 [o] 170 171 When extracting files, this option will cause **llvm-ar** to preserve the 172 original modification times of the files it writes. 173 174 175 176 [u] 177 178 When replacing existing files in the archive, only replace those files that have 179 a time stamp than the time stamp of the member in the archive. 180 181 182 183 184 Modifiers (generic) 185 ~~~~~~~~~~~~~~~~~~~ 186 187 188 The modifiers below may be applied to any operation. 189 190 191 [c] 192 193 For all operations, **llvm-ar** will always create the archive if it doesn't 194 exist. Normally, **llvm-ar** will print a warning message indicating that the 195 archive is being created. Using this modifier turns off that warning. 196 197 198 199 [s] 200 201 This modifier requests that an archive index (or symbol table) be added to the 202 archive. This is the default mode of operation. The symbol table will contain 203 all the externally visible functions and global variables defined by all the 204 bitcode files in the archive. 205 206 207 208 [S] 209 210 This modifier is the opposite of the *s* modifier. It instructs **llvm-ar** to 211 not build the symbol table. If both *s* and *S* are used, the last modifier to 212 occur in the options will prevail. 213 214 215 216 [v] 217 218 This modifier instructs **llvm-ar** to be verbose about what it is doing. Each 219 editing operation taken against the archive will produce a line of output saying 220 what is being done. 221 222 223 224 225 226 STANDARDS 227 --------- 228 229 230 The **llvm-ar** utility is intended to provide a superset of the IEEE Std 1003.2 231 (POSIX.2) functionality for ``ar``. **llvm-ar** can read both SVR4 and BSD4.4 (or 232 Mac OS X) archives. If the ``f`` modifier is given to the ``x`` or ``r`` operations 233 then **llvm-ar** will write SVR4 compatible archives. Without this modifier, 234 **llvm-ar** will write BSD4.4 compatible archives that have long names 235 immediately after the header and indicated using the "#1/ddd" notation for the 236 name in the header. 237 238 239 FILE FORMAT 240 ----------- 241 242 243 The file format for LLVM Archive files is similar to that of BSD 4.4 or Mac OSX 244 archive files. In fact, except for the symbol table, the ``ar`` commands on those 245 operating systems should be able to read LLVM archive files. The details of the 246 file format follow. 247 248 Each archive begins with the archive magic number which is the eight printable 249 characters "!<arch>\n" where \n represents the newline character (0x0A). 250 Following the magic number, the file is composed of even length members that 251 begin with an archive header and end with a \n padding character if necessary 252 (to make the length even). Each file member is composed of a header (defined 253 below), an optional newline-terminated "long file name" and the contents of 254 the file. 255 256 The fields of the header are described in the items below. All fields of the 257 header contain only ASCII characters, are left justified and are right padded 258 with space characters. 259 260 261 name - char[16] 262 263 This field of the header provides the name of the archive member. If the name is 264 longer than 15 characters or contains a slash (/) character, then this field 265 contains ``#1/nnn`` where ``nnn`` provides the length of the name and the ``#1/`` 266 is literal. In this case, the actual name of the file is provided in the ``nnn`` 267 bytes immediately following the header. If the name is 15 characters or less, it 268 is contained directly in this field and terminated with a slash (/) character. 269 270 271 272 date - char[12] 273 274 This field provides the date of modification of the file in the form of a 275 decimal encoded number that provides the number of seconds since the epoch 276 (since 00:00:00 Jan 1, 1970) per Posix specifications. 277 278 279 280 uid - char[6] 281 282 This field provides the user id of the file encoded as a decimal ASCII string. 283 This field might not make much sense on non-Unix systems. On Unix, it is the 284 same value as the st_uid field of the stat structure returned by the stat(2) 285 operating system call. 286 287 288 289 gid - char[6] 290 291 This field provides the group id of the file encoded as a decimal ASCII string. 292 This field might not make much sense on non-Unix systems. On Unix, it is the 293 same value as the st_gid field of the stat structure returned by the stat(2) 294 operating system call. 295 296 297 298 mode - char[8] 299 300 This field provides the access mode of the file encoded as an octal ASCII 301 string. This field might not make much sense on non-Unix systems. On Unix, it 302 is the same value as the st_mode field of the stat structure returned by the 303 stat(2) operating system call. 304 305 306 307 size - char[10] 308 309 This field provides the size of the file, in bytes, encoded as a decimal ASCII 310 string. 311 312 313 314 fmag - char[2] 315 316 This field is the archive file member magic number. Its content is always the 317 two characters back tick (0x60) and newline (0x0A). This provides some measure 318 utility in identifying archive files that have been corrupted. 319 320 321 offset - vbr encoded 32-bit integer 322 323 The offset item provides the offset into the archive file where the bitcode 324 member is stored that is associated with the symbol. The offset value is 0 325 based at the start of the first "normal" file member. To derive the actual 326 file offset of the member, you must add the number of bytes occupied by the file 327 signature (8 bytes) and the symbol tables. The value of this item is encoded 328 using variable bit rate encoding to reduce the size of the symbol table. 329 Variable bit rate encoding uses the high bit (0x80) of each byte to indicate 330 if there are more bytes to follow. The remaining 7 bits in each byte carry bits 331 from the value. The final byte does not have the high bit set. 332 333 334 335 length - vbr encoded 32-bit integer 336 337 The length item provides the length of the symbol that follows. Like this 338 *offset* item, the length is variable bit rate encoded. 339 340 341 342 symbol - character array 343 344 The symbol item provides the text of the symbol that is associated with the 345 *offset*. The symbol is not terminated by any character. Its length is provided 346 by the *length* field. Note that is allowed (but unwise) to use non-printing 347 characters (even 0x00) in the symbol. This allows for multiple encodings of 348 symbol names. 349 350 351 352 353 EXIT STATUS 354 ----------- 355 356 357 If **llvm-ar** succeeds, it will exit with 0. A usage error, results 358 in an exit code of 1. A hard (file system typically) error results in an 359 exit code of 2. Miscellaneous or unknown errors result in an 360 exit code of 3. 361 362 363 SEE ALSO 364 -------- 365 366 367 ar(1) 368
