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// Copyright 2011 Google Inc. All Rights Reserved.
//
// Licensed under the Apache License, Version 2.0 (the "License");
// you may not use this file except in compliance with the License.
// You may obtain a copy of the License at
//
// http://www.apache.org/licenses/LICENSE-2.0
//
// Unless required by applicable law or agreed to in writing, software
// distributed under the License is distributed on an "AS IS" BASIS,
// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
// See the License for the specific language governing permissions and
// limitations under the License.
#include "depfile_parser.h"
#include "util.h"
DepfileParser::DepfileParser(DepfileParserOptions options)
: options_(options)
{
}
// A note on backslashes in Makefiles, from reading the docs:
// Backslash-newline is the line continuation character.
// Backslash-# escapes a # (otherwise meaningful as a comment start).
// Backslash-% escapes a % (otherwise meaningful as a special).
// Finally, quoting the GNU manual, "Backslashes that are not in danger
// of quoting ‘%’ characters go unmolested."
// How do you end a line with a backslash? The netbsd Make docs suggest
// reading the result of a shell command echoing a backslash!
//
// Rather than implement all of above, we follow what GCC/Clang produces:
// Backslashes escape a space or hash sign.
// When a space is preceded by 2N+1 backslashes, it is represents N backslashes
// followed by space.
// When a space is preceded by 2N backslashes, it represents 2N backslashes at
// the end of a filename.
// A hash sign is escaped by a single backslash. All other backslashes remain
// unchanged.
//
// If anyone actually has depfiles that rely on the more complicated
// behavior we can adjust this.
bool DepfileParser::Parse(string* content, string* err) {
// in: current parser input point.
// end: end of input.
// parsing_targets: whether we are parsing targets or dependencies.
char* in = &(*content)[0];
char* end = in + content->size();
bool have_target = false;
bool have_secondary_target_on_this_rule = false;
bool have_newline_since_primary_target = false;
bool warned_distinct_target_lines = false;
bool parsing_targets = true;
while (in < end) {
bool have_newline = false;
// out: current output point (typically same as in, but can fall behind
// as we de-escape backslashes).
char* out = in;
// filename: start of the current parsed filename.
char* filename = out;
for (;;) {
// start: beginning of the current parsed span.
const char* start = in;
char* yymarker = NULL;
/*!re2c
re2c:define:YYCTYPE = "unsigned char";
re2c:define:YYCURSOR = in;
re2c:define:YYLIMIT = end;
re2c:define:YYMARKER = yymarker;
re2c:yyfill:enable = 0;
re2c:indent:top = 2;
re2c:indent:string = " ";
nul = "\000";
newline = '\r'?'\n';
'\\\\'* '\\ ' {
// 2N+1 backslashes plus space -> N backslashes plus space.
int len = (int)(in - start);
int n = len / 2 - 1;
if (out < start)
memset(out, '\\', n);
out += n;
*out++ = ' ';
continue;
}
'\\\\'+ ' ' {
// 2N backslashes plus space -> 2N backslashes, end of filename.
int len = (int)(in - start);
if (out < start)
memset(out, '\\', len - 1);
out += len - 1;
break;
}
'\\'+ '#' {
// De-escape hash sign, but preserve other leading backslashes.
int len = (int)(in - start);
if (len > 2 && out < start)
memset(out, '\\', len - 2);
out += len - 2;
*out++ = '#';
continue;
}
'$$' {
// De-escape dollar character.
*out++ = '$';
continue;
}
'\\'+ [^\000\r\n] | [a-zA-Z0-9+,/_:.~()}{%=@\x5B\x5D!\x80-\xFF-]+ {
// Got a span of plain text.
int len = (int)(in - start);
// Need to shift it over if we're overwriting backslashes.
if (out < start)
memmove(out, start, len);
out += len;
continue;
}
nul {
break;
}
'\\' newline {
// A line continuation ends the current file name.
break;
}
newline {
// A newline ends the current file name and the current rule.
have_newline = true;
break;
}
[^] {
// For any other character (e.g. whitespace), swallow it here,
// allowing the outer logic to loop around again.
break;
}
*/
}
int len = (int)(out - filename);
const bool is_dependency = !parsing_targets;
if (len > 0 && filename[len - 1] == ':') {
len--; // Strip off trailing colon, if any.
parsing_targets = false;
have_target = true;
}
if (len > 0) {
if (is_dependency) {
if (have_secondary_target_on_this_rule) {
if (!have_newline_since_primary_target) {
*err = "depfile has multiple output paths";
return false;
} else if (options_.depfile_distinct_target_lines_action_ ==
kDepfileDistinctTargetLinesActionError) {
*err =
"depfile has multiple output paths (on separate lines)"
" [-w depfilemulti=err]";
return false;
} else {
if (!warned_distinct_target_lines) {
warned_distinct_target_lines = true;
Warning("depfile has multiple output paths (on separate lines); "
"continuing anyway [-w depfilemulti=warn]");
}
continue;
}
}
ins_.push_back(StringPiece(filename, len));
} else if (!out_.str_) {
out_ = StringPiece(filename, len);
} else if (out_ != StringPiece(filename, len)) {
have_secondary_target_on_this_rule = true;
}
}
if (have_newline) {
// A newline ends a rule so the next filename will be a new target.
parsing_targets = true;
have_secondary_target_on_this_rule = false;
if (have_target) {
have_newline_since_primary_target = true;
}
}
}
if (!have_target) {
*err = "expected ':' in depfile";
return false;
}
return true;
}
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