1 files changed, 283 insertions, 0 deletions
diff --git a/zutils.cc b/zutils.cc
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--- /dev/null
+++ b/zutils.cc
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+/* Zutils - Utilities dealing with compressed files
+   Copyright (C) 2009-2021 Antonio Diaz Diaz.
+
+   This program is free software: you can redistribute it and/or modify
+   it under the terms of the GNU General Public License as published by
+   the Free Software Foundation, either version 2 of the License, or
+   (at your option) any later version.
+
+   This program 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 General Public License for more details.
+
+   You should have received a copy of the GNU General Public License
+   along with this program.  If not, see <http://www.gnu.org/licenses/>.
+*/
+
+#define _FILE_OFFSET_BITS 64
+
+#include <cerrno>
+#include <csignal>
+#include <cstdio>
+#include <cstdlib>
+#include <cstring>
+#include <string>
+#include <vector>
+#include <stdint.h>
+#include <unistd.h>
+#include <sys/wait.h>
+
+#include "rc.h"
+#include "zutils.h"
+
+
+namespace {
+
+inline bool isvalid_ds( const uint8_t ds )	// lzip valid dictionary_size
+  {
+  enum { min_dictionary_size = 1 << 12,
+         max_dictionary_size = 1 << 29 };
+  unsigned dictionary_size = ( 1 << ( ds & 0x1F ) );
+  if( dictionary_size > min_dictionary_size )
+    dictionary_size -= ( dictionary_size / 16 ) * ( ( ds >> 5 ) & 7 );
+  return ( dictionary_size >= min_dictionary_size &&
+           dictionary_size <= max_dictionary_size );
+  }
+
+
+/* Returns -1 if child not terminated, 2 in case of error, or exit status of
+   child process 'pid'.
+*/
+int child_status( const pid_t pid, const char * const name )
+  {
+  int status;
+  while( true )
+    {
+    const int tmp = waitpid( pid, &status, WNOHANG );
+    if( tmp == -1 && errno != EINTR )
+      {
+      if( verbosity >= 0 )
+        std::fprintf( stderr, "%s: Error checking status of '%s': %s\n",
+                      program_name, name, std::strerror( errno ) );
+      _exit( 2 );
+      }
+    if( tmp == 0 ) return -1;			// child not terminated
+    if( tmp == pid ) break;			// child terminated
+    }
+  if( WIFEXITED( status ) ) return WEXITSTATUS( status );
+  if( WIFSIGNALED( status ) && WTERMSIG( status ) == SIGPIPE ) return 0;
+  return 2;
+  }
+
+} // end namespace
+
+
+/* Returns the number of bytes really read.
+   If (returned value < size) and (errno == 0), means EOF was reached.
+*/
+int readblock( const int fd, uint8_t * const buf, const int size )
+  {
+  int sz = 0;
+  errno = 0;
+  while( sz < size )
+    {
+    const int n = read( fd, buf + sz, size - sz );
+    if( n > 0 ) sz += n;
+    else if( n == 0 ) break;				// EOF
+    else if( errno != EINTR ) break;
+    errno = 0;
+    }
+  return sz;
+  }
+
+
+/* Returns the number of bytes really written.
+   If (returned value < size), it is always an error.
+*/
+int writeblock( const int fd, const uint8_t * const buf, const int size )
+  {
+  int sz = 0;
+  errno = 0;
+  while( sz < size )
+    {
+    const int n = write( fd, buf + sz, size - sz );
+    if( n > 0 ) sz += n;
+    else if( n < 0 && errno != EINTR ) break;
+    errno = 0;
+    }
+  return sz;
+  }
+
+
+// Empty filename means stdin.
+//
+bool feed_data( const std::string & filename, const int infd, const int outfd,
+                const uint8_t * magic_data, const int magic_size )
+  {
+  if( magic_size && writeblock( outfd, magic_data, magic_size ) != magic_size )
+    { show_error( "Write error", errno ); return false; }
+  enum { buffer_size = 4096 };
+  uint8_t buffer[buffer_size];
+  while( true )
+    {
+    const int size = readblock( infd, buffer, buffer_size );
+    if( size != buffer_size && errno )
+      { const char * const name = filename.empty() ? "-" : filename.c_str();
+        show_file_error( name, "Read error", errno ); return false; }
+    if( size > 0 && writeblock( outfd, buffer, size ) != size )
+      { show_error( "Write error", errno ); return false; }
+    if( size < buffer_size ) break;
+    }
+  return true;
+  }
+
+
+bool good_status( const Children & children, const bool finished )
+  {
+  bool error = false;
+  for( int i = 0; i < 2; ++i )
+    {
+    const pid_t pid = children.pid[i];
+    if( pid )
+      {
+      const char * const name =
+        ( i == 0 ) ? "data feeder" : children.compressor_name;
+      // even if compressor finished, trailing data may remain in data feeder
+      if( i == 0 || !finished )
+        {
+        const int tmp = child_status( pid, name );
+        if( tmp < 0 )				// child not terminated
+          { kill( pid, SIGTERM ); wait_for_child( pid, name ); }
+        else if( tmp != 0 ) error = true;	// child status != 0
+        }
+      else
+        if( wait_for_child( pid, name ) != 0 ) error = true;
+      }
+    }
+  return !error;
+  }
+
+
+bool set_data_feeder( const std::string & filename, int * const infdp,
+                      Children & children, int format_index )
+  {
+  uint8_t magic_data[magic_buf_size];
+  int magic_size = 0;
+  if( format_index < 0 )
+    format_index = test_format( *infdp, magic_data, &magic_size );
+  children.compressor_name = get_compressor_name( format_index );
+
+  if( children.compressor_name )	// compressed
+    {
+    int fda[2];				// pipe from feeder
+    int fda2[2];			// pipe from compressor
+    if( pipe( fda ) < 0 || pipe( fda2 ) < 0 )
+      { show_error( "Can't create pipe", errno ); return false; }
+    const int old_infd = *infdp;
+    *infdp = fda2[0];
+    const pid_t pid = fork();
+    if( pid == 0 )			// child 1 (compressor feeder)
+      {
+      if( close( fda[0] ) != 0 ||
+          close( fda2[0] ) != 0 || close( fda2[1] ) != 0 ||
+          !feed_data( filename, old_infd, fda[1], magic_data, magic_size ) )
+        _exit( 2 );
+      if( close( fda[1] ) != 0 )
+        { show_close_error(); _exit( 2 ); }
+      _exit( 0 );
+      }
+    if( pid < 0 )			// parent
+      { show_fork_error( "data feeder" ); return false; }
+
+    const pid_t pid2 = fork();
+    if( pid2 == 0 )			// child 2 (compressor)
+      {
+      if( dup2( fda[0], STDIN_FILENO ) >= 0 &&
+          dup2( fda2[1], STDOUT_FILENO ) >= 0 &&
+          close( fda[0] ) == 0 && close( fda[1] ) == 0 &&
+          close( fda2[0] ) == 0 && close( fda2[1] ) == 0 )
+        {
+        const std::vector< std::string > & compressor_args =
+          get_compressor_args( format_index );
+        const int size = compressor_args.size();
+        const char ** const argv = new const char *[size+3];
+        argv[0] = children.compressor_name;
+        for( int i = 0; i < size; ++i )
+          argv[i+1] = compressor_args[i].c_str();
+        argv[size+1] = ( verbosity >= 0 ) ? "-d" : "-dq";
+        argv[size+2] = 0;
+        execvp( argv[0], (char **)argv );
+        }
+      show_exec_error( children.compressor_name );
+      _exit( 2 );
+      }
+    if( pid2 < 0 )			// parent
+      { show_fork_error( children.compressor_name ); return false; }
+
+    close( fda[0] ); close( fda[1] ); close( fda2[1] );
+    children.pid[0] = pid;
+    children.pid[1] = pid2;
+    }
+  else					// uncompressed
+    {
+    int fda[2];				// pipe from feeder
+    if( pipe( fda ) < 0 )
+      { show_error( "Can't create pipe", errno ); return false; }
+    const int old_infd = *infdp;
+    *infdp = fda[0];
+    const pid_t pid = fork();
+    if( pid == 0 )			// child (feeder)
+      {
+      if( close( fda[0] ) != 0 ||
+          !feed_data( filename, old_infd, fda[1], magic_data, magic_size ) )
+        _exit( 2 );
+      if( close( fda[1] ) != 0 )
+        { show_close_error(); _exit( 2 ); }
+      _exit( 0 );
+      }
+    if( pid < 0 )			// parent
+      { show_fork_error( "data feeder" ); return false; }
+    close( fda[1] );
+    children.pid[0] = pid;
+    children.pid[1] = 0;
+    }
+  return true;
+  }
+
+
+// Returns format index or -1 if uncompressed
+//
+int test_format( const int infd, uint8_t magic_data[],
+                 int * const magic_sizep )
+  {
+  enum { bzip2_magic_size = 3,
+          gzip_magic_size = 2,
+          lzip_magic_size = 5,
+            xz_magic_size = 5 };
+  const uint8_t bzip2_magic[bzip2_magic_size] =
+    { 0x42, 0x5A, 0x68 };				// "BZh"
+  const uint8_t gzip_magic[gzip_magic_size] =
+    { 0x1F, 0x8B };
+  const uint8_t lzip_magic[lzip_magic_size] =
+    { 0x4C, 0x5A, 0x49, 0x50, 0x01 };			// "LZIP\001"
+  const uint8_t xz_magic[xz_magic_size] =
+    { 0xFD, 0x37, 0x7A, 0x58, 0x5A };			// 0xFD, "7zXZ"
+
+  *magic_sizep = readblock( infd, magic_data, magic_buf_size );
+  if( *magic_sizep == magic_buf_size )
+    {
+    if( std::memcmp( magic_data, bzip2_magic, bzip2_magic_size ) == 0 &&
+        magic_data[3] >= '1' && magic_data[3] <= '9' &&
+        std::memcmp( magic_data + 4, "1AY&SY", 6 ) == 0 )
+      return fmt_bz2;
+    if( std::memcmp( magic_data, gzip_magic, gzip_magic_size ) == 0 )
+      return fmt_gz;
+    if( std::memcmp( magic_data, lzip_magic, lzip_magic_size ) == 0 &&
+        isvalid_ds( magic_data[lzip_magic_size] ) )
+      return fmt_lz;
+    if( std::memcmp( magic_data, xz_magic, xz_magic_size ) == 0 )
+      return fmt_xz;
+    }
+  return -1;
+  }