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Diffstat (limited to 'iconv/gconv_charset.c')
| -rw-r--r-- | iconv/gconv_charset.c | 218 |
1 files changed, 218 insertions, 0 deletions
diff --git a/iconv/gconv_charset.c b/iconv/gconv_charset.c new file mode 100644 index 0000000000..6ccd0773cc --- /dev/null +++ b/iconv/gconv_charset.c @@ -0,0 +1,218 @@ +/* Charset name normalization. + Copyright (C) 2020 Free Software Foundation, Inc. + This file is part of the GNU C Library. + + The GNU C Library is free software; you can redistribute it and/or + modify it under the terms of the GNU Lesser General Public + License as published by the Free Software Foundation; either + version 2.1 of the License, or (at your option) any later version. + + The GNU C Library is distributed in the hope that it will be useful, + but WITHOUT ANY WARRANTY; without even the implied warranty of + MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU + Lesser General Public License for more details. + + You should have received a copy of the GNU Lesser General Public + License along with the GNU C Library; if not, see + <http://www.gnu.org/licenses/>. */ + + +#include <stdlib.h> +#include <ctype.h> +#include <locale.h> +#include <stdbool.h> +#include <string.h> +#include <sys/stat.h> +#include "gconv_int.h" +#include "gconv_charset.h" + + +/* This function returns a pointer to the last suffix in a conversion code + string. Valid suffixes matched by this function are of the form: '/' or ',' + followed by arbitrary text that doesn't contain '/' or ','. It does not + edit the string in any way. The caller is expected to parse the suffix and + remove it (by e.g. truncating the string) before the next call. */ +static char * +find_suffix (char *s) +{ + /* The conversion code is in the form of a triplet, separated by '/' chars. + The third component of the triplet contains suffixes. If we don't have two + slashes, we don't have a suffix. */ + + int slash_count = 0; + char *suffix_term = NULL; + + for (int i = 0; s[i] != '\0'; i++) + switch (s[i]) + { + case '/': + slash_count++; + /* Fallthrough */ + case ',': + suffix_term = &s[i]; + } + + if (slash_count >= 2) + return suffix_term; + + return NULL; +} + + +struct gconv_parsed_code +{ + char *code; + bool translit; + bool ignore; +}; + + +/* This function parses an iconv_open encoding PC.CODE, strips any suffixes + (such as TRANSLIT or IGNORE) from it and sets corresponding flags in it. */ +static void +gconv_parse_code (struct gconv_parsed_code *pc) +{ + pc->translit = false; + pc->ignore = false; + + while (1) + { + /* First drop any trailing whitespaces and separators. */ + size_t len = strlen (pc->code); + while ((len > 0) + && (isspace (pc->code[len - 1]) + || pc->code[len - 1] == ',' + || pc->code[len - 1] == '/')) + len--; + + pc->code[len] = '\0'; + + if (len == 0) + return; + + char * suffix = find_suffix (pc->code); + if (suffix == NULL) + { + /* At this point, we have processed and removed all suffixes from the + code and what remains of the code is suffix free. */ + return; + } + else + { + /* A suffix is processed from the end of the code array going + backwards, one suffix at a time. The suffix is an index into the + code character array and points to: one past the end of the code + and any unprocessed suffixes, and to the beginning of the suffix + currently being processed during this iteration. We must process + this suffix and then drop it from the code by terminating the + preceding text with NULL. + + We want to allow and recognize suffixes such as: + + "/TRANSLIT" i.e. single suffix + "//TRANSLIT" i.e. single suffix and multiple separators + "//TRANSLIT/IGNORE" i.e. suffixes separated by "/" + "/TRANSLIT//IGNORE" i.e. suffixes separated by "//" + "//IGNORE,TRANSLIT" i.e. suffixes separated by "," + "//IGNORE," i.e. trailing "," + "//TRANSLIT/" i.e. trailing "/" + "//TRANSLIT//" i.e. trailing "//" + "/" i.e. empty suffix. + + Unknown suffixes are silently discarded and ignored. */ + + if ((__strcasecmp_l (suffix, + GCONV_TRIPLE_SEPARATOR + GCONV_TRANSLIT_SUFFIX, + _nl_C_locobj_ptr) == 0) + || (__strcasecmp_l (suffix, + GCONV_SUFFIX_SEPARATOR + GCONV_TRANSLIT_SUFFIX, + _nl_C_locobj_ptr) == 0)) + pc->translit = true; + + if ((__strcasecmp_l (suffix, + GCONV_TRIPLE_SEPARATOR + GCONV_IGNORE_ERRORS_SUFFIX, + _nl_C_locobj_ptr) == 0) + || (__strcasecmp_l (suffix, + GCONV_SUFFIX_SEPARATOR + GCONV_IGNORE_ERRORS_SUFFIX, + _nl_C_locobj_ptr) == 0)) + pc->ignore = true; + + /* We just processed this suffix. We can now drop it from the + code string by truncating it at the suffix's position. */ + suffix[0] = '\0'; + } + } +} + + +/* This function accepts the charset names of the source and destination of the + conversion and populates *conv_spec with an equivalent conversion + specification that may later be used by __gconv_open. The charset names + might contain options in the form of suffixes that alter the conversion, + e.g. "ISO-10646/UTF-8/TRANSLIT". It processes the charset names, ignoring + and truncating any suffix options in fromcode, and processing and truncating + any suffix options in tocode. Supported suffix options ("TRANSLIT" or + "IGNORE") when found in tocode lead to the corresponding flag in *conv_spec + to be set to true. Unrecognized suffix options are silently discarded. If + the function succeeds, it returns conv_spec back to the caller. It returns + NULL upon failure. conv_spec must be allocated and freed by the caller. */ +struct gconv_spec * +__gconv_create_spec (struct gconv_spec *conv_spec, const char *fromcode, + const char *tocode) +{ + struct gconv_parsed_code pfc, ptc; + struct gconv_spec *ret = NULL; + + pfc.code = __strdup (fromcode); + ptc.code = __strdup (tocode); + + if ((pfc.code == NULL) + || (ptc.code == NULL)) + goto out; + + gconv_parse_code (&pfc); + gconv_parse_code (&ptc); + + /* We ignore suffixes in the fromcode because that is how the current + implementation has always handled them. Only suffixes in the tocode are + processed and handled. The reality is that invalid input in the input + character set should only be ignored if the fromcode specifies IGNORE. + The current implementation ignores invalid intput in the input character + set if the tocode contains IGNORE. We preserve this behavior for + backwards compatibility. In the future we may split the handling of + IGNORE to allow a finer grained specification of ignorning invalid input + and/or ignoring invalid output. */ + conv_spec->translit = ptc.translit; + conv_spec->ignore = ptc.ignore; + + /* 3 extra bytes because 1 extra for '\0', and 2 extra so strip might + be able to add one or two trailing '/' characters if necessary. */ + conv_spec->fromcode = malloc (strlen (fromcode) + 3); + if (conv_spec->fromcode == NULL) + goto out; + + conv_spec->tocode = malloc (strlen (tocode) + 3); + if (conv_spec->tocode == NULL) + { + free (conv_spec->fromcode); + conv_spec->fromcode = NULL; + goto out; + } + + /* Strip unrecognized characters and ensure that the code has two '/' + characters as per conversion code triplet specification. */ + strip (conv_spec->fromcode, pfc.code); + strip (conv_spec->tocode, ptc.code); + ret = conv_spec; + +out: + free (pfc.code); + free (ptc.code); + + return ret; +} +libc_hidden_def (__gconv_create_spec) |