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+<html><head><meta http-equiv="Content-Type" content="text/html; charset=ISO-8859-1"><title>Encoding Conversion</title><meta name="generator" content="DocBook XSL Stylesheets V1.61.2"><link rel="home" href="index.html" title="Libxml Tutorial"><link rel="up" href="index.html" title="Libxml Tutorial"><link rel="previous" href="ar01s08.html" title="Retrieving Attributes"><link rel="next" href="apa.html" title="A. Compilation"></head><body bgcolor="white" text="black" link="#0000FF" vlink="#840084" alink="#0000FF"><div class="navheader"><table width="100%" summary="Navigation header"><tr><th colspan="3" align="center">Encoding Conversion</th></tr><tr><td width="20%" align="left"><a accesskey="p" href="ar01s08.html">Prev</a> </td><th width="60%" align="center"> </th><td width="20%" align="right"> <a accesskey="n" href="apa.html">Next</a></td></tr></table><hr></div><div class="sect1" lang="en"><div class="titlepage"><div><div><h2 class="title" style="clear: both"><a name="xmltutorialconvert"></a>Encoding Conversion</h2></div></div><div></div></div><p><a class="indexterm" name="id2587348"></a>
+Data encoding compatibility problems are one of the most common
+ difficulties encountered by programmers new to <span class="acronym">XML</span> in
+ general and <span class="application">libxml</span> in particular. Thinking
+ through the design of your application in light of this issue will help
+ avoid difficulties later. Internally, <span class="application">libxml</span>
+ stores and manipulates data in the UTF-8 format. Data used by your program
+ in other formats, such as the commonly used ISO-8859-1 encoding, must be
+ converted to UTF-8 before passing it to <span class="application">libxml</span>
+ functions. If you want your program's output in an encoding other than
+ UTF-8, you also must convert it.</p><p><span class="application">Libxml</span> uses
+ <span class="application">iconv</span> if it is available to convert
+ data. Without <span class="application">iconv</span>, only UTF-8, UTF-16 and
+ ISO-8859-1 can be used as external formats. With
+ <span class="application">iconv</span>, any format can be used provided
+ <span class="application">iconv</span> is able to convert it to and from
+ UTF-8. Currently <span class="application">iconv</span> supports about 150
+ different character formats with ability to convert from any to any. While
+ the actual number of supported formats varies between implementations, every
+ <span class="application">iconv</span> implementation is almost guaranteed to
+ support every format anyone has ever heard of.</p><div class="warning" style="margin-left: 0.5in; margin-right: 0.5in;"><table border="0" summary="Warning"><tr><td rowspan="2" align="center" valign="top" width="25"><img alt="[Warning]" src="images/warning.png"></td><th align="left">Warning</th></tr><tr><td colspan="2" align="left" valign="top"><p>A common mistake is to use different formats for the internal data
+ in different parts of one's code. The most common case is an application
+ that assumes ISO-8859-1 to be the internal data format, combined with
+ <span class="application">libxml</span>, which assumes UTF-8 to be the
+ internal data format. The result is an application that treats internal
+ data differently, depending on which code section is executing. The one or
+ the other part of code will then, naturally, misinterpret the data.
+ </p></td></tr></table></div><p>This example constructs a simple document, then adds content provided
+ at the command line to the document's root element and outputs the results
+ to <tt class="filename">stdout</tt> in the proper encoding. For this example, we
+ use ISO-8859-1 encoding. The encoding of the string input at the command
+ line is converted from ISO-8859-1 to UTF-8. Full code: <a href="aph.html" title="H. Code for Encoding Conversion Example">Appendix H, <i>Code for Encoding Conversion Example</i></a></p><p>The conversion, encapsulated in the example code in the
+ <tt class="function">convert</tt> function, uses
+ <span class="application">libxml's</span>
+ <tt class="function">xmlFindCharEncodingHandler</tt> function:
+ </p><pre class="programlisting">
+ <a name="handlerdatatype"></a><img src="images/callouts/1.png" alt="1" border="0">xmlCharEncodingHandlerPtr handler;
+ <a name="calcsize"></a><img src="images/callouts/2.png" alt="2" border="0">size = (int)strlen(in)+1;
+ out_size = size*2-1;
+ out = malloc((size_t)out_size);
+
+&#8230;
+ <a name="findhandlerfunction"></a><img src="images/callouts/3.png" alt="3" border="0">handler = xmlFindCharEncodingHandler(encoding);
+&#8230;
+ <a name="callconversionfunction"></a><img src="images/callouts/4.png" alt="4" border="0">handler-&gt;input(out, &amp;out_size, in, &amp;temp);
+&#8230;
+ <a name="outputencoding"></a><img src="images/callouts/5.png" alt="5" border="0">xmlSaveFormatFileEnc("-", doc, encoding, 1);
+ </pre><p>
+ </p><div class="calloutlist"><table border="0" summary="Callout list"><tr><td width="5%" valign="top" align="left"><a href="#handlerdatatype"><img src="images/callouts/1.png" alt="1" border="0"></a> </td><td valign="top" align="left"><p><tt class="varname">handler</tt> is declared as a pointer to an
+ <tt class="function">xmlCharEncodingHandler</tt> function.</p></td></tr><tr><td width="5%" valign="top" align="left"><a href="#calcsize"><img src="images/callouts/2.png" alt="2" border="0"></a> </td><td valign="top" align="left"><p>The <tt class="function">xmlCharEncodingHandler</tt> function needs
+ to be given the size of the input and output strings, which are
+ calculated here for strings <tt class="varname">in</tt> and
+ <tt class="varname">out</tt>.</p></td></tr><tr><td width="5%" valign="top" align="left"><a href="#findhandlerfunction"><img src="images/callouts/3.png" alt="3" border="0"></a> </td><td valign="top" align="left"><p><tt class="function">xmlFindCharEncodingHandler</tt> takes as its
+ argument the data's initial encoding and searches
+ <span class="application">libxml's</span> built-in set of conversion
+ handlers, returning a pointer to the function or NULL if none is
+ found.</p></td></tr><tr><td width="5%" valign="top" align="left"><a href="#callconversionfunction"><img src="images/callouts/4.png" alt="4" border="0"></a> </td><td valign="top" align="left"><p>The conversion function identified by <tt class="varname">handler</tt>
+ requires as its arguments pointers to the input and output strings,
+ along with the length of each. The lengths must be determined
+ separately by the application.</p></td></tr><tr><td width="5%" valign="top" align="left"><a href="#outputencoding"><img src="images/callouts/5.png" alt="5" border="0"></a> </td><td valign="top" align="left"><p>To output in a specified encoding rather than UTF-8, we use
+ <tt class="function">xmlSaveFormatFileEnc</tt>, specifying the
+ encoding.</p></td></tr></table></div><p>
+ </p></div><div class="navfooter"><hr><table width="100%" summary="Navigation footer"><tr><td width="40%" align="left"><a accesskey="p" href="ar01s08.html">Prev</a> </td><td width="20%" align="center"><a accesskey="u" href="index.html">Up</a></td><td width="40%" align="right"> <a accesskey="n" href="apa.html">Next</a></td></tr><tr><td width="40%" align="left" valign="top">Retrieving Attributes </td><td width="20%" align="center"><a accesskey="h" href="index.html">Home</a></td><td width="40%" align="right" valign="top"> A. Compilation</td></tr></table></div></body></html>
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keyword argument 'store'. Pass to with-writable-file. (with-writable-file, call-with-writable-file): new store argument. (deduplicate): pass store to replace-with-link. Signed-off-by: Ludovic Courtès <ludo@gnu.org> Caleb Ristvedt 2020-09-14.dir-locals.el: fix call-with-{retrying-}transaction indenting....* .dir-locals.el (call-with-transaction, call-with-retrying-transaction): change scheme-indent-function property from 2 to 1. Signed-off-by: Ludovic Courtès <ludo@gnu.org> Caleb Ristvedt 2020-08-26.dir-locals.el: Add indentation rule for 'package/inherit'....* .dir-locals.el (scheme-mode): Add 'package/inherit'. Ludovic Courtès 2020-06-25deduplication: Use 'dynamic-wind' when changing permissions of the parent....Suggested by Caleb Ristvedt <caleb.ristvedt@cune.org>. * guix/store/deduplication.scm (call-with-writable-file): New procedure. (with-writable-file): New macro. (replace-with-link): Use it. Ludovic Courtès 2020-06-16channels: 'latest-channel-instance' authenticates Git checkouts....Fixes <https://bugs.gnu.org/22883>. * guix/channels.scm (<channel>)[introduction]: New field. (<channel-introduction>): New record type. (%guix-channel-introduction): New variable. (%default-channels): Use it. (<channel-metadata>)[keyring-reference]: New field. (%default-keyring-reference): New variable. (read-channel-metadata, read-channel-metadata-from-source): Initialize the 'keyring-reference' field. (commit-short-id, verify-introductory-commit) (authenticate-channel): New procedures. (latest-channel-instance): Call 'authenticate-channel' when CHANNEL has an introduction. * tests/channels.scm (gpg+git-available?, commit-id-string): New procedures. ("authenticate-channel, wrong first commit signer"): ("authenticate-channel, .guix-authorizations"): New tests. * doc/guix.texi (Invoking guix pull): Mention authentication. Ludovic Courtès 2020-06-10database: separate transaction-handling and retry-handling....Previously call-with-transaction would both retry when SQLITE_BUSY errors were thrown and do what its name suggested (start and rollback/commit a transaction). This changes it to do only what its name implies, which simplifies its implementation. Retrying is provided by the new call-with-SQLITE_BUSY-retrying procedure. * guix/store/database.scm (call-with-transaction): no longer restarts, new #:restartable? argument controls whether "begin" or "begin immediate" is used. (call-with-SQLITE_BUSY-retrying, call-with-retrying-transaction, call-with-retrying-savepoint): new procedures. (register-items): use call-with-retrying-transaction to preserve old behavior. * .dir-locals.el (call-with-retrying-transaction, call-with-retrying-savepoint): add indentation information. Caleb Ristvedt 2020-06-10database: ensure update-or-insert is run within a transaction...update-or-insert can break if an insert occurs between when it decides whether to update or insert and when it actually performs that operation. Putting the check and the update/insert operation in the same transaction ensures that the update/insert will only succeed if no other write has occurred in the middle. * guix/store/database.scm (call-with-savepoint): new procedure. (update-or-insert): use call-with-savepoint to ensure the read and the insert/update occur within the same transaction. Caleb Ristvedt 2020-06-10database: rewrite query procedures in terms of with-statement....Most of our queries would fail to finalize their statements properly if sqlite returned an error during their execution. This resolves that, and also makes them somewhat more concise as a side-effect. This also makes some small changes to improve certain queries where behavior was strange or overly verbose. * guix/store/database.scm (call-with-statement): new procedure. (with-statement): new macro. (last-insert-row-id, path-id, update-or-insert, add-references): rewrite to use with-statement. (update-or-insert): factor last-insert-row-id out of the end of both branches. (add-references): remove pointless last-insert-row-id call. * .dir-locals.el (with-statement): add indenting information. Caleb Ristvedt 2020-06-06ui: 'display-search-results' automatically invokes the pager....* guix/ui.scm (call-with-paginated-output-port): New procedure. (with-paginated-output-port): New macro. (display-search-results): Use it instead of displaying a hint. Ludovic Courtès 2020-06-05git-authenticate: Add tests....* guix/tests/git.scm (call-with-environment-variables) (with-environment-variables): Remove. * guix/tests/git.scm (populate-git-repository): Add clauses for signed commits and signed merges. * guix/tests/gnupg.scm: New file. * tests/git-authenticate.scm: New file. * tests/ed25519bis.key, tests/ed25519bis.sec: New files. * Makefile.am (dist_noinst_DATA): Add 'guix/tests/gnupg.scm'. (SCM_TESTS): Add 'tests/git-authenticate.scm'. (EXTRA_DIST): Add tests/ed25519bis.{key,sec}. Ludovic Courtès 2020-05-16gexp: Add 'let-system'....* guix/gexp.scm (<system-binding>): New record type. (let-system): New macro. (system-binding-compiler): New procedure. (default-expander): Add 'self-quoting?' case. (self-quoting?): New procedure. (lower-inputs): Add 'filterm'. Pass the result of 'mapm/accumulate-builds' through FILTERM. (gexp->sexp)[self-quoting?]: Remove. * tests/gexp.scm ("let-system", "let-system, target") ("let-system, ungexp-native, target") ("let-system, nested"): New tests. * doc/guix.texi (G-Expressions): Document it. Ludovic Courtès 2020-03-22store: Add 'with-build-handler'....* guix/store.scm (current-build-prompt): New variable. (call-with-build-handler, invoke-build-handler): New procedures. (with-build-handler): New macro. * tests/store.scm ("with-build-handler"): New test. Ludovic Courtès 2020-03-12gexp: Add 'with-parameters'....* guix/gexp.scm (<parameterized>): New record type. (with-parameters): New macro. (compile-parameterized): New gexp compiler. * tests/gexp.scm ("with-parameters for %current-system") ("with-parameters for %current-target-system") ("with-parameters + file-append"): New tests. * doc/guix.texi (G-Expressions): Document it. Ludovic Courtès 2019-11-29ui: Factorize 'with-profile-lock'....* guix/ui.scm (profile-lock-handler, profile-lock-file): New procedures. (with-profile-lock): New macro. * guix/scripts/package.scm (process-actions): Use 'with-profile-lock' instead of 'with-file-lock/no-wait'. * guix/scripts/pull.scm (guix-pull): Likewise. Ludovic Courtès 2019-11-19pull: Acquire a lock for the target profile....This is a followup to b1fb663404894268b5ee92c040f12c52c0bee425. * guix/scripts/pull.scm (guix-pull): Wrap 'run-with-store' call in 'with-file-lock/no-wait'. Ludovic Courtès 2019-09-23git: Add 'commit-difference'....* guix/git.scm (commit-closure, commit-difference): New procedures. * guix/tests/git.scm, tests/git.scm: New files. * Makefile.am (dist_noinst_DATA): Add guix/tests/git.scm. (SCM_TESTS): Add tests/git.scm. Ludovic Courtès 2019-06-05syscalls: Add 'with-file-lock' macro....* guix/scripts/offload.scm (lock-file, unlock-file, with-file-lock): Move to... * guix/build/syscalls.scm: ... here. Ludovic Courtès 2019-05-27publish: Add support for lzip....* guix/scripts/publish.scm (show-help, %options): Support '-C METHOD' and '-C METHOD:LEVEL'. (default-compression): New procedure. (bake-narinfo+nar): Add lzip. (nar-response-port): Likewise. (string->compression-type): New procedure. (make-request-handler): Generalize /nar/gzip handler to handle /nar/lzip as well. * tests/publish.scm ("/nar/lzip/*"): New test. ("/*.narinfo with lzip compression"): New test. * doc/guix.texi (Invoking guix publish): Document it. (Requirements): Mention lzlib. Ludovic Courtès 2019-03-07database: Make 'register-items' transactional....* guix/store/database.scm (SQLITE_BUSY, register-output-sql): New variables. (add-references): Don't try finalizing after each use, only after all the uses (otherwise a finalized statement would be used if #:cache? was #f). (call-with-transaction): New procedure. (register-items): Use call-with-transaction to prevent broken intermediate states from being visible. * .dir-locals.el (call-with-transaction): indent it. Signed-off-by: Ludovic Courtès <ludo@gnu.org> Caleb Ristvedt 2019-01-11status: Add 'with-status-verbosity'....* guix/status.scm (logger-for-level, call-with-status-verbosity): New procedures. (with-status-verbosity): New macro. * guix/scripts/environment.scm (guix-environment): Use 'with-status-verbosity' instead of 'with-status-report'. * guix/scripts/pack.scm (guix-pack): Likewise. * guix/scripts/package.scm (guix-package): Likewise. * guix/scripts/pull.scm (guix-pull): Likewise. * guix/scripts/system.scm (guix-system): Likewise. * build-aux/run-system-tests.scm (run-system-tests): Likewise. Ludovic Courtès 2018-10-19tests: Run 'guix pack' tests using the external store....Fixes <https://bugs.gnu.org/32184>. * guix/tests.scm (call-with-external-store): New procedure. (with-external-store): New macro. * tests/pack.scm (%store): Remove. (test-assertm): Add 'store' parameter. ("self-contained-tarball"): Wrap in 'with-external-store'. * tests/guix-pack.sh: Connect to the external store, if possible, by setting NIX_STORE_DIR and GUIX_DAEMON_SOCKET. Remove most uses of '--bootstrap'. Ludovic Courtès 2018-09-27Add (guix status) and use it for pretty colored output....* guix/progress.scm (progress-reporter/trace): New procedure. (%progress-interval): New variable. (progress-reporter/file): Use it. * guix/scripts/build.scm (set-build-options-from-command-line): Pass #:print-extended-build-trace?. (%default-options): Add 'print-extended-build-trace?'. (guix-build): Parameterize CURRENT-TERMINAL-COLUMNS. Use 'build-status-updater'. * guix/scripts/environment.scm (%default-options): Add 'print-extended-build-trace?'. (guix-environment): Wrap body in 'with-status-report'. * guix/scripts/pack.scm (%default-options): Add 'print-build-trace?' and 'print-extended-build-trace?'. (guix-pack): Wrap body in 'with-status-report'. * guix/scripts/package.scm (%default-options, guix-package): Likewise. * guix/scripts/system.scm (%default-options, guix-system): Likewise. * guix/scripts/pull.scm (%default-options, guix-pull): Likewise. * guix/scripts/substitute.scm (progress-report-port): Don't call STOP when TOTAL is zero. (process-substitution): Add #:print-build-trace? and honor it. (guix-substitute)[print-build-trace?]: New variable. Pass #:print-build-trace? to 'process-substitution'. * guix/status.scm: New file. * guix/store.scm (set-build-options): Add #:print-extended-build-trace?; pass it into PAIRS. (%protocol-version): Bump. (protocol-version, nix-server-version): New procedures. (current-store-protocol-version): New variable. (with-store, build-things): Parameterize it. * guix/ui.scm (build-output-port): Remove. (colorize-string): Export. * po/guix/POTFILES.in: Add guix/status.scm. * tests/status.scm: New file. * Makefile.am (SCM_TESTS): Add it. * nix/libstore/worker-protocol.hh (PROTOCOL_VERSION): Bump to 0x162. * nix/libstore/build.cc (DerivationGoal::registerOutputs) (SubstitutionGoal::finished): Print a "@ hash-mismatch" trace before throwing. Ludovic Courtès