Add #! support to execve(2).
This commit is contained in:
Jonas 'Sortie' Termansen
parent
3577cb81fe
commit
f8c5adf20f
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@ -25,6 +25,7 @@
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#include <sys/wait.h>
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#include <assert.h>
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#include <ctype.h>
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#include <errno.h>
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#include <limits.h>
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#include <msr.h>
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@ -1035,6 +1036,100 @@ int Process::Execute(const char* programname, const uint8_t* program,
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return 0;
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}
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static
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const char* shebang_lookup_environment(const char* name, char* const* envp)
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{
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size_t equalpos = strcspn(name, "=");
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if ( name[equalpos] == '=' )
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return NULL;
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size_t namelen = equalpos;
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for ( size_t i = 0; envp[i]; i++ )
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{
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if ( strncmp(name, envp[i], namelen) )
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continue;
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if ( envp[i][namelen] != '=' )
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continue;
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return envp[i] + namelen + 1;
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}
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return NULL;
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}
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static char* shebang_tokenize(char** saved)
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{
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char* data = *saved;
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if ( !data )
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return *saved = NULL;
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while ( data[0] && isspace(data[0]) )
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data++;
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if ( !data[0] )
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return *saved = NULL;
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size_t input = 0;
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size_t output = 0;
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bool singly = false;
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bool doubly = false;
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bool escaped = false;
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for ( ; data[input]; input++ )
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{
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char c = data[input];
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if ( !escaped && !singly && !doubly && isspace(c) )
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break;
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if ( !escaped && !doubly && c == '\'' )
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{
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singly = !singly;
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continue;
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}
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if ( !escaped && !singly && c == '"' )
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{
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doubly = !doubly;
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continue;
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}
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if ( !singly && !escaped && c == '\\' )
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{
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escaped = true;
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continue;
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}
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if ( escaped )
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{
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switch ( c )
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{
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case 'a': c = '\a'; break;
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case 'b': c = '\b'; break;
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case 'e': c = '\e'; break;
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case 'f': c = '\f'; break;
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case 'n': c = '\n'; break;
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case 'r': c = '\r'; break;
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case 't': c = '\t'; break;
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case 'v': c = '\v'; break;
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default: break;
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};
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}
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escaped = false;
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data[output++] = c;
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}
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if ( data[input] )
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*saved = data + input + 1;
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else
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*saved = NULL;
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data[output] = '\0';
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return data;
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}
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static size_t shebang_count_arguments(char* line)
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{
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size_t result = 0;
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while ( shebang_tokenize(&line) )
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result++;
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return result;
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}
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// NOTE: The PATH-searching logic is repeated multiple places. Until this logic
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// can be shared somehow, you need to keep this comment in sync as well
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// as the logic in these files:
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// * kernel/process.cpp
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// * libc/unistd/execvpe.cpp
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// * utils/which.cpp
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// NOTO: See comments in execvpe() for algorithmic commentary.
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static
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int sys_execve_kernel(const char* filename,
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int argc,
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@ -1077,8 +1172,133 @@ int sys_execve_kernel(const char* filename,
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int result = process->Execute(filename, buffer, filesize, argc, argv, envc, envp, regs);
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if ( result == 0 || errno != ENOEXEC ||
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filesize < 2 || buffer[0] != '#' || buffer[1] != '!' )
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return delete[] buffer, result;
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size_t line_length = 0;
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while ( line_length < filesize && buffer[2 + line_length] != '\n' )
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line_length++;
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if ( line_length == filesize )
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return delete[] buffer, errno = ENOEXEC, -1;
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char* line = new char[line_length+1];
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if ( !line )
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return delete[] buffer, -1;
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memcpy(line, buffer + 2, line_length);
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line[line_length] = '\0';
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delete[] buffer;
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char* line_clone = String::Clone(line);
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if ( !line_clone )
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return delete[] line, -1;
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size_t argument_count = shebang_count_arguments(line_clone);
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delete[] line_clone;
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if ( !argument_count || INT_MAX < argument_count )
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return delete[] line, errno = ENOEXEC, -1;
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int sb_argc = (int) argument_count;
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char** sb_argv = new char*[sb_argc];
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if ( !sb_argv )
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return delete[] line, -1;
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char* sb_saved = line;
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for ( int i = 0; i < sb_argc; i++ )
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sb_argv[i] = shebang_tokenize(&sb_saved);
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if ( INT_MAX - argc <= sb_argc )
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return delete[] sb_argv, delete[] line, errno = EOVERFLOW, -1;
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if ( !sb_argv[0][0] )
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return delete[] sb_argv, delete[] line, errno = ENOENT, -1;
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int new_argc = sb_argc + argc;
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char** new_argv = new char*[new_argc + 1];
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if ( !new_argv )
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return delete[] sb_argv, delete[] line, -1;
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for ( int i = 0; i < sb_argc; i++ )
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new_argv[i] = sb_argv[i];
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new_argv[sb_argc + 0] = (char*) filename;
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for ( int i = 1; i < argc; i++ )
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new_argv[sb_argc + i] = argv[i];
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new_argv[new_argc] = (char*) NULL;
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result = -1;
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// (See the above comment block before editing this searching logic)
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const char* path = shebang_lookup_environment("PATH", envp);
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bool search_path = !strchr(sb_argv[0], '/') && path;
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bool any_tries = false;
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bool any_eacces = false;
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const char* new_argv0 = sb_argv[0];
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while ( search_path && *path )
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{
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size_t len = strcspn(path, ":");
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if ( !len )
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{
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path++;
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continue;
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}
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any_tries = true;
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char* dirpath = strndup(path, len);
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if ( !dirpath )
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return -1;
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if ( (path += len)[0] == ':' )
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path++;
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while ( len && dirpath[len - 1] == '/' )
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dirpath[--len] = '\0';
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char* fullpath;
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if ( asprintf(&fullpath, "%s/%s", dirpath, sb_argv[0]) < 0 )
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return free(dirpath), -1;
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result = sys_execve_kernel(fullpath, new_argc, new_argv, envc, envp, regs);
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free(fullpath);
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free(dirpath);
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if ( result == 0 )
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break;
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if ( errno == ENOENT )
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continue;
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if ( errno == ELOOP ||
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errno == EISDIR ||
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errno == ENAMETOOLONG ||
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errno == ENOTDIR )
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continue;
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if ( errno == EACCES )
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{
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any_eacces = true;
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continue;
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}
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if ( errno == EACCES )
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{
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any_eacces = true;
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continue;
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}
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break;
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}
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if ( !any_tries )
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result = sys_execve_kernel(new_argv0, new_argc, new_argv, envc, envp, regs);
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if ( result < 0 && any_eacces )
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errno = EACCES;
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delete[] new_argv;
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delete[] sb_argv;
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delete[] line;
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return result;
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}
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@ -91,6 +91,7 @@ int execvpe_attempt(const char* filename,
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// NOTE: The PATH-searching logic is repeated multiple places. Until this logic
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// can be shared somehow, you need to keep this comment in sync as well
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// as the logic in these files:
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// * kernel/process.cpp
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// * libc/unistd/execvpe.cpp
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// * utils/which.cpp
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@ -38,6 +38,7 @@
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// NOTE: The PATH-searching logic is repeated multiple places. Until this logic
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// can be shared somehow, you need to keep this comment in sync as well
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// as the logic in these files:
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// * kernel/process.cpp
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// * libc/unistd/execvpe.cpp
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// * utils/which.cpp
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// NOTO: See comments in execvpe() for algorithmic commentary.
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