diff options
Diffstat (limited to 'butl/process.cxx')
| -rw-r--r-- | butl/process.cxx | 335 |
1 files changed, 235 insertions, 100 deletions
diff --git a/butl/process.cxx b/butl/process.cxx index 80b97cc..cceceed 100644 --- a/butl/process.cxx +++ b/butl/process.cxx @@ -7,6 +7,8 @@ #ifndef _WIN32 # include <unistd.h> // execvp, fork, dup2, pipe, chdir, *_FILENO, getpid # include <sys/wait.h> // waitpid +# include <sys/types.h> // _stat +# include <sys/stat.h> // _stat(), S_IS* #else # include <butl/win32-utility> @@ -16,13 +18,23 @@ # include <sys/types.h> // stat # include <sys/stat.h> // stat(), S_IS* +# ifdef _MSC_VER // Unlikely to be fixed in newer versions. +# define S_ISREG(m) (((m) & S_IFMT) == S_IFREG) + +# define STDIN_FILENO 0 +# define STDOUT_FILENO 1 +# define STDERR_FILENO 2 +# endif // _MSC_VER + # include <memory> // unique_ptr +# include <cstdlib> // __argv[] -# include <butl/path> # include <butl/win32-utility> #endif #include <cassert> +#include <cstddef> // size_t +#include <cstring> // strlen(), strchr() #include <butl/utility> // casecmp() #include <butl/fdstream> // fdnull(), fdclose() @@ -33,15 +45,6 @@ using namespace std; using namespace butl::win32; #endif -#ifdef _MSC_VER // Unlikely to be fixed in newer versions. -#define S_ISREG(m) (((m) & S_IFMT) == S_IFREG) -# define S_ISDIR(m) (((m) & S_IFMT) == S_IFDIR) - -# define STDIN_FILENO 0 -# define STDOUT_FILENO 1 -# define STDERR_FILENO 2 -#endif // _MSC_VER - namespace butl { class auto_fd @@ -89,8 +92,96 @@ namespace butl #ifndef _WIN32 + process_path process:: + path_search (const char*& args0) + { + // Note that there is a similar version for Win32. + + typedef path::traits traits; + + const char* f (args0); + size_t fn (strlen (f)); + + path rp, ep; // recall & effective + auto search = [&ep, f, fn] (const char* d, size_t dn) -> bool + { + string s (move (ep).string ()); // Reuse buffer. + + if (dn != 0) + { + s.assign (d, dn); + + if (!traits::is_separator (s.back ())) + s += traits::directory_separator; + } + + s.append (f, fn); + ep = path (move (s)); // Move back into result. + + // Check that the file exists and has at least one executable bit set. + // This way we get a bit closer to the "continue search on EACCES" + // semantics (see below). + // + struct stat si; + return (stat (ep.string ().c_str (), &si) == 0 && + S_ISREG (si.st_mode) && + (si.st_mode & (S_IEXEC | S_IXGRP | S_IXOTH)) != 0); + }; + + for (;;) // The "goto end" loop. + { + // If there is a directory component in the file, then search does not + // apply. + // + if (traits::find_separator (f, fn) != nullptr) + break; + + // The search order is documented in exec(3). Some of the differences + // compared to exec*p() functions: + // + // 1. If there no PATH, we don't default to current directory/_CS_PATH. + // 2. We do not continue searching on EACCES from execve(). + // 3. We do not execute via default shell on ENOEXEC from execve(). + // + { + const char* b (getenv ("PATH")); + + for (const char* e; b != nullptr; b = (e != nullptr ? e + 1 : e)) + { + e = strchr (b, traits::path_separator); + + // Empty path (i.e., a double colon or a colon at the beginning or + // end of PATH) means search in the current dirrectory. + // + if (search (b, e != nullptr ? e - b : strlen (b))) + break; + } + + if (b != nullptr) + break; + } + + // Did not find anything. + // + throw process_error (ENOENT, false); + } + + // Found the file and the result is in rp and ep, both of which can be + // empty. + // + process_path r (f, + rp.empty () ? nullptr : &(args0 = rp.string ().c_str ())); + + r.recall = move (rp); + r.effect = move (ep); + + return r; + } + process:: - process (const char* cwd, char const* const args[], int in, int out, int err) + process (const char* cwd, + const process_path& pp, const char* args[], + int in, int out, int err) { using pipe = auto_fd[2]; @@ -176,7 +267,11 @@ namespace butl if (cwd != nullptr && *cwd != '\0' && chdir (cwd) != 0) fail (true); - if (execvp (args[0], const_cast<char**> (&args[0])) == -1) + const char* file (pp.effect.empty () + ? args[0] + : pp.effect.string ().c_str ()); + + if (execv (file, const_cast<char**> (&args[0])) == -1) fail (true); } @@ -188,9 +283,10 @@ namespace butl } process:: - process (const char* cwd, char const* const args[], + process (const char* cwd, + const process_path& pp, const char* args[], process& in, int out, int err) - : process (cwd, args, in.in_ofd, out, err) + : process (cwd, pp, args, in.in_ofd, out, err) { assert (in.in_ofd != -1); // Should be a pipe. close (in.in_ofd); // Close it on our side. @@ -250,102 +346,155 @@ namespace butl #else // _WIN32 - // Why do we search for the program ourselves when CreateProcess() can be - // made to do that for us? Well, that's a bit of a historic mystery. We - // could use it to disable search in the current working directory. Or we - // could handle batch files automatically. - // - static path - path_search (const path& f) + process_path process:: + path_search (const char*& args0) { + // Note that there is a similar version for Win32. + typedef path::traits traits; - // If there is a directory component in the file, then the PATH search - // does not apply. + const char* f (args0); + size_t fn (strlen (f)); + + // Unless there is already the .exe extension, then we will need to add + // it. Note that running .bat files requires starting cmd.exe and passing + // the batch file as an argument (see CreateProcess() for deails). So + // if/when we decide to support those, it will have to be handled + // differently. // - if (!f.simple ()) - return f; + bool ext; + { + const char* e (traits::find_extension (f, fn)); + ext = (e == nullptr || casecmp (e, ".exe") != 0); + } - path r; - auto search = [&r, &f] (const char* d, size_t n) -> bool + path rp, ep; // recall & effective + auto search = [&ep, f, fn, ext] (const char* d, size_t dn) -> bool { - string s (move (r).string ()); // Reuse buffer. + string s (move (ep).string ()); // Reuse buffer. - if (n != 0) + if (dn != 0) { - s.assign (d, n); + s.assign (d, dn); if (!traits::is_separator (s.back ())) s += traits::directory_separator; } - s += f.string (); - r = path (move (s)); // Move back into result. + s.append (f, fn); + ep = path (move (s)); // Move back into result. - // Unless there is already the .exe extension, add it. Note that running - // .bat files requires starting cmd.exe and passing the batch file as an - // argument (see CreateProcess() for deails). So if/when we decide to - // support those, it will have to be handled differently. + // Add the .exe extension if necessary. // - const char* e (r.extension ()); - if (e == nullptr || casecmp (e, "exe") != 0) - r += ".exe"; + if (ext) + ep += ".exe"; // Only check that the file exists since the executable mode is set // according to the file extension. // - struct stat si; - return stat (r.string ().c_str (), &si) == 0 && S_ISREG (si.st_mode); + struct _stat si; + return _stat (ep.string ().c_str (), &si) == 0 && S_ISREG (si.st_mode); }; - // The search order is documented in CreateProcess(). First we look in - // the directory of the parent executable. - // + for (;;) // The "goto end" loop. { - char d[_MAX_PATH + 1]; - DWORD n (GetModuleFileName (NULL, d, _MAX_PATH + 1)); + // If there is a directory component in the file, then search does not + // apply. But we may still need to append the extension. + // + if (traits::find_separator (f, fn) != nullptr) + { + if (ext) + { + ep = path (f, fn); + ep += ".exe"; + } - if (n == 0 || n == _MAX_PATH + 1) // Failed or truncated. - throw process_error (last_error_msg ()); + break; + } - const char* p (traits::rfind_separator (d, n)); - assert (p != nullptr); + // The search order is documented in CreateProcess(). First we look in + // the directory of the parent executable. + // + { + char d[_MAX_PATH + 1]; + DWORD n (GetModuleFileName (NULL, d, _MAX_PATH + 1)); - if (search (d, p - d + 1)) // Include trailing slash. - return r; - } + if (n == 0 || n == _MAX_PATH + 1) // Failed or truncated. + throw process_error (last_error_msg ()); - // Next look in the current working directory. Crazy, I know. - // - if (search ("", 0)) - return r; + const char* p (traits::rfind_separator (d, n)); + assert (p != nullptr); - // Finally, search in PATH. - // - if (const char* s = getenv ("PATH")) - { - string ps (s); + if (search (d, p - d + 1)) // Include trailing slash. + { + // In this case we have to set the recall path. + // + // Note that the directory we have extracted is always absolute but + // the parent's recall path (argv[0]) might be relative. It seems, + // ideally, we would want to use parent's argv[0] dir (if any) to + // form the recall path. In particular, if the parent has no + // directory, then it means it was found via the standard search + // (e.g., PATH) and then so should the child. + // + // How do we get the parent's argv[0]? Luckily, here is __argv on + // Windows. + // + const char* d (__argv[0]); + size_t n (strlen (d)); + if (const char* p = traits::rfind_separator (d, n)) + { + string s (d, p - d + 1); // Include trailing slash. + s.append (f, fn); + rp = path (move (s)); + } + + break; + } + } - for (size_t b (0), e (ps.find (traits::path_separator)); - b != string::npos;) + // Next look in the current working directory. Crazy, I know. + // + // The recall path is the same as initial, though it might not be a bad + // idea to prepend .\ for clarity. + // + if (search ("", 0)) + break; + + // Finally, search in PATH. Recall is unchanged. + // { - // Empty path (i.e., a double colon or a colon at the beginning or end - // of PATH) means search in the current dirrectory. - // - if (search (ps.c_str () + b, (e != string::npos ? e : ps.size ()) - b)) - return r; + const char* b (getenv ("PATH")); - if (e == string::npos) - b = e; - else + for (const char* e; b != nullptr; b = (e != nullptr ? e + 1 : e)) { - b = e + 1; - e = ps.find (traits::path_separator, b); + e = strchr (b, traits::path_separator); + + // Empty path (i.e., a double colon or a colon at the beginning or + // end of PATH) means search in the current dirrectory. + // + if (search (b, e != nullptr ? e - b : strlen (b))) + break; } + + if (b != nullptr) + break; } + + // Did not find anything. + // + throw process_error (ENOENT); } - return path (); + // Found the file and the result is in rp and ep, both of which can be + // empty. + // + process_path r (f, + rp.empty () ? nullptr : &(args0 = rp.string ().c_str ())); + + r.recall = move (rp); + r.effect = move (ep); + + return r; } class auto_handle @@ -392,7 +541,9 @@ namespace butl }; process:: - process (const char* cwd, char const* const args[], int in, int out, int err) + process (const char* cwd, + const process_path& pp, const char* args[], + int in, int out, int err) { using pipe = auto_handle[2]; @@ -481,32 +632,15 @@ namespace butl // Create the process. // - path file (args[0]); - - // Do PATH search. - // - if (file.simple ()) - { - file = path_search (file); - - if (file.empty ()) - fail ("file not found"); - } - else - { - // Unless there is already the .exe extension, add it. See path_search() - // for details. - // - const char* e (file.extension ()); - if (e == nullptr || casecmp (e, "exe") != 0) - file += ".exe"; - } + const char* file (pp.effect.empty () + ? args[0] + : pp.effect.string ().c_str ()); // Serialize the arguments to string. // string cmd_line; - for (char const* const* p (args); *p != 0; ++p) + for (const char* const* p (args); *p != 0; ++p) { if (p != args) cmd_line += ' '; @@ -575,7 +709,7 @@ namespace butl fail ("invalid file descriptor"); if (!CreateProcess ( - file.string ().c_str (), + file, const_cast<char*> (cmd_line.c_str ()), 0, // Process security attributes. 0, // Primary thread security attributes. @@ -621,9 +755,10 @@ namespace butl } process:: - process (const char* cwd, char const* const args[], + process (const char* cwd, + const process_path& pp, const char* args[], process& in, int out, int err) - : process (cwd, args, in.in_ofd, out, err) + : process (cwd, pp, args, in.in_ofd, out, err) { assert (in.in_ofd != -1); // Should be a pipe. _close (in.in_ofd); // Close it on our side. |