Mercurial > vim
view src/beval.c @ 34394:a400c8f9506f v9.1.0123
patch 9.1.0123: MS-Windows: system() may deadlock
Commit: https://github.com/vim/vim/commit/52ecc76c7fa1865603f27bc838efaeaa03cad77c
Author: GuyBrush <miguel.barro@live.com>
Date: Wed Feb 21 20:16:38 2024 +0100
patch 9.1.0123: MS-Windows: system() may deadlock
Problem: MS-Windows: system() may deadlock when calling binaries that
expect stdin
Solution: Ignore the SHELL_EXPAND flag
(GuyBrush)
This happens on binaries that expect stdin. For example:
:echo system("xxd")
will cause a deadlock.
SHELL_EXPAND is a flag devoted to support the linux implementation of
the backtick-expansion mechanism.
On linux backtic-expansion relies in the function mch_expand_wildchars()
(os_unix.c) that delegates on each specific shell (bash, sh, csh, zsh)
the expansion. Basically it composes a shell command that does the
expansion and redirects the output to a file and call_shell() it. On
windows backtick-expansion is performed by Vim itself.
On linux SHELL_EXPAND modifies how mch_call_shell_fork() (os_unix.c)
works. This function:
- relies on posix fork() to spawn a child process to execute a
external command.
- Child and parent process communicate using pipes (or pseudoterminal
if available).
User input (type ahead content) is processed in a loop only if
!(SHELL_EXPAND || SHELL_COOKED).
Though signals are used to detect Ctrl-C in all cases (the input
loop is not necessary to interrupt the function).
In the backtick-expansion the external command is the shell command
that provides the expansion. For the child redirection:
- SHELL_EXPAND replaces stdin, stdout & stderr to /dev/null. This is
why the shell command composed includes redirection (otherwise
output would be lost).
- !SHELL_EXPAND replaces stdin, stdout & stderr with the parent
created pipes (or pseudoterminal).
Note that the use of SIGINT signal prevents mch_call_shell_fork()
from hanging vim.
On Windows mch_system_piped() (os_win32.c) (which is only used when the
GUI is running) mimics mch_call_shell_fork() (os_unix.c).
Win32 lacks fork() and relies on CreateProcessW() and only has pipe
support (not pseudoterminal) which makes the implementation much
different.
But, the key idea is that windows lacks signals, the OS provides support
for console apps but gvim is not one. The only way of detecting a Ctrl-C
is actually processing user input (type ahead content). By ignoring the
user input under SHELL_EXPAND the function can hang gvim.
Ignoring SHELL_EXPAND flag has no consequence in Windows because as
mentioned above it is only meaningful in linux.
closes: #13988
Signed-off-by: GuyBrush <miguel.barro@live.com>
Signed-off-by: Christian Brabandt <cb@256bit.org>
author | Christian Brabandt <cb@256bit.org> |
---|---|
date | Wed, 21 Feb 2024 20:30:02 +0100 |
parents | 8fc442c731ca |
children |
line wrap: on
line source
/* vi:set ts=8 sts=4 sw=4 noet: * * VIM - Vi IMproved by Bram Moolenaar * Visual Workshop integration by Gordon Prieur * * Do ":help uganda" in Vim to read copying and usage conditions. * Do ":help credits" in Vim to see a list of people who contributed. * See README.txt for an overview of the Vim source code. */ #include "vim.h" #if defined(FEAT_BEVAL) || defined(FEAT_PROP_POPUP) || defined(PROTO) /* * Find text under the mouse position "row" / "col". * If "getword" is TRUE the returned text in "*textp" is not the whole line but * the relevant word in allocated memory. * Return OK if found. * Return FAIL if not found, no text at the mouse position. */ int find_word_under_cursor( int mouserow, int mousecol, int getword, int flags, // flags for find_ident_at_pos() win_T **winp, // can be NULL linenr_T *lnump, // can be NULL char_u **textp, int *colp, // column where mouse hovers, can be NULL int *startcolp) // column where text starts, can be NULL { int row = mouserow; int col = mousecol; int scol; win_T *wp; char_u *lbuf; linenr_T lnum; *textp = NULL; wp = mouse_find_win(&row, &col, FAIL_POPUP); if (wp == NULL || row < 0 || row >= wp->w_height || col >= wp->w_width) return FAIL; // Found a window and the cursor is in the text. Now find the line // number. if (mouse_comp_pos(wp, &row, &col, &lnum, NULL)) return FAIL; // position is below the last line // Not past end of the file. lbuf = ml_get_buf(wp->w_buffer, lnum, FALSE); if (col > win_linetabsize(wp, lnum, lbuf, (colnr_T)MAXCOL)) return FAIL; // past end of line // Not past end of line. if (getword) { // For Netbeans we get the relevant part of the line // instead of the whole line. int len; pos_T *spos = NULL, *epos = NULL; if (VIsual_active) { if (LT_POS(VIsual, curwin->w_cursor)) { spos = &VIsual; epos = &curwin->w_cursor; } else { spos = &curwin->w_cursor; epos = &VIsual; } } col = vcol2col(wp, lnum, col, NULL); scol = col; if (VIsual_active && wp->w_buffer == curwin->w_buffer && (lnum == spos->lnum ? col >= (int)spos->col : lnum > spos->lnum) && (lnum == epos->lnum ? col <= (int)epos->col : lnum < epos->lnum)) { // Visual mode and pointing to the line with the // Visual selection: return selected text, with a // maximum of one line. if (spos->lnum != epos->lnum || spos->col == epos->col) return FAIL; lbuf = ml_get_buf(curwin->w_buffer, VIsual.lnum, FALSE); len = epos->col - spos->col; if (*p_sel != 'e') len += mb_ptr2len(lbuf + epos->col); lbuf = vim_strnsave(lbuf + spos->col, len); lnum = spos->lnum; col = spos->col; scol = col; } else { // Find the word under the cursor. ++emsg_off; len = find_ident_at_pos(wp, lnum, (colnr_T)col, &lbuf, &scol, flags); --emsg_off; if (len == 0) return FAIL; lbuf = vim_strnsave(lbuf, len); } } else scol = col; if (winp != NULL) *winp = wp; if (lnump != NULL) *lnump = lnum; *textp = lbuf; if (colp != NULL) *colp = col; if (startcolp != NULL) *startcolp = scol; return OK; } #endif #if defined(FEAT_BEVAL) || defined(PROTO) /* * Get the text and position to be evaluated for "beval". * If "getword" is TRUE the returned text is not the whole line but the * relevant word in allocated memory. * Returns OK or FAIL. */ int get_beval_info( BalloonEval *beval, int getword, win_T **winp, linenr_T *lnump, char_u **textp, int *colp) { int row = mouse_row; int col = mouse_col; # ifdef FEAT_BEVAL_GUI if (gui.in_use) { row = Y_2_ROW(beval->y); col = X_2_COL(beval->x); } # endif if (find_word_under_cursor(row, col, getword, FIND_IDENT + FIND_STRING + FIND_EVAL, winp, lnump, textp, colp, NULL) == OK) { # ifdef FEAT_VARTABS vim_free(beval->vts); beval->vts = tabstop_copy((*winp)->w_buffer->b_p_vts_array); if ((*winp)->w_buffer->b_p_vts_array != NULL && beval->vts == NULL) { if (getword) vim_free(*textp); return FAIL; } # endif beval->ts = (*winp)->w_buffer->b_p_ts; return OK; } return FAIL; } /* * Show a balloon with "mesg" or "list". * Hide the balloon when both are NULL. */ void post_balloon(BalloonEval *beval UNUSED, char_u *mesg, list_T *list UNUSED) { # ifdef FEAT_BEVAL_TERM # ifdef FEAT_GUI if (!gui.in_use) # endif ui_post_balloon(mesg, list); # endif # ifdef FEAT_BEVAL_GUI if (gui.in_use) // GUI can't handle a list gui_mch_post_balloon(beval, mesg); # endif } /* * Returns TRUE if the balloon eval has been enabled: * 'ballooneval' for the GUI and 'balloonevalterm' for the terminal. * Also checks if the screen isn't scrolled up. */ int can_use_beval(void) { return (0 #ifdef FEAT_BEVAL_GUI || (gui.in_use && p_beval) #endif #ifdef FEAT_BEVAL_TERM || ( # ifdef FEAT_GUI !gui.in_use && # endif p_bevalterm) #endif ) && msg_scrolled == 0; } # ifdef FEAT_EVAL /* * Evaluate the expression 'bexpr' and set the text in the balloon 'beval'. */ static void bexpr_eval( BalloonEval *beval, char_u *bexpr, win_T *wp, linenr_T lnum, int col, char_u *text) { win_T *cw; long winnr = 0; buf_T *save_curbuf; int use_sandbox; static char_u *result = NULL; size_t len; sctx_T save_sctx = current_sctx; // Convert window pointer to number. for (cw = firstwin; cw != wp; cw = cw->w_next) ++winnr; set_vim_var_nr(VV_BEVAL_BUFNR, (long)wp->w_buffer->b_fnum); set_vim_var_nr(VV_BEVAL_WINNR, winnr); set_vim_var_nr(VV_BEVAL_WINID, wp->w_id); set_vim_var_nr(VV_BEVAL_LNUM, (long)lnum); set_vim_var_nr(VV_BEVAL_COL, (long)(col + 1)); set_vim_var_string(VV_BEVAL_TEXT, text, -1); vim_free(text); /* * Temporarily change the curbuf, so that we can determine whether * the buffer-local balloonexpr option was set insecurely. */ save_curbuf = curbuf; curbuf = wp->w_buffer; use_sandbox = was_set_insecurely((char_u *)"balloonexpr", *curbuf->b_p_bexpr == NUL ? 0 : OPT_LOCAL); curbuf = save_curbuf; if (use_sandbox) ++sandbox; ++textlock; if (bexpr == p_bexpr) { sctx_T *sp = get_option_sctx("balloonexpr"); if (sp != NULL) current_sctx = *sp; } else current_sctx = curbuf->b_p_script_ctx[BV_BEXPR]; vim_free(result); result = eval_to_string(bexpr, TRUE, TRUE); // Remove one trailing newline, it is added when the result was a // list and it's hardly ever useful. If the user really wants a // trailing newline he can add two and one remains. if (result != NULL) { len = STRLEN(result); if (len > 0 && result[len - 1] == NL) result[len - 1] = NUL; } if (use_sandbox) --sandbox; --textlock; current_sctx = save_sctx; set_vim_var_string(VV_BEVAL_TEXT, NULL, -1); if (result != NULL && result[0] != NUL) post_balloon(beval, result, NULL); // The 'balloonexpr' evaluation may show something on the screen // that requires a screen update. if (must_redraw) redraw_after_callback(FALSE, FALSE); } # endif /* * Common code, invoked when the mouse is resting for a moment. */ void general_beval_cb(BalloonEval *beval, int state UNUSED) { #ifdef FEAT_EVAL win_T *wp; int col; linenr_T lnum; char_u *text; char_u *bexpr; #endif static int recursive = FALSE; // Don't do anything when 'ballooneval' is off, messages scrolled the // windows up or we have no beval area. if (!can_use_beval() || beval == NULL) return; // Don't do this recursively. Happens when the expression evaluation // takes a long time and invokes something that checks for CTRL-C typed. if (recursive) return; recursive = TRUE; #ifdef FEAT_EVAL if (get_beval_info(beval, TRUE, &wp, &lnum, &text, &col) == OK) { bexpr = (*wp->w_buffer->b_p_bexpr == NUL) ? p_bexpr : wp->w_buffer->b_p_bexpr; if (*bexpr != NUL) { bexpr_eval(beval, bexpr, wp, lnum, col, text); recursive = FALSE; return; } } #endif #ifdef FEAT_NETBEANS_INTG if (bevalServers & BEVAL_NETBEANS) netbeans_beval_cb(beval, state); #endif recursive = FALSE; } #endif