filter.c

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#include "config.h"
#include <errno.h>
#include <stdbool.h>
#include <stdio.h>
#include <string.h>
#include <sys/types.h>
#include "mutt/lib.h"
#include "gui/lib.h"
#include "expando.h"
#include "node.h"
#include "render.h"

bool check_for_pipe(struct ExpandoNode *root)
{
  if (!root)
    return false;
 
  struct ExpandoNode *last = node_last(root);
  if (!last || (last->type != ENT_TEXT))
    return false;
 
  size_t len = mutt_str_len(last->text);
  if (len < 1)
    return false;
 
  if (last->text[len - 1] != '|')
    return false;
 
  // Count any preceding backslashes
  int count = 0;
  for (int i = len - 2; i >= 0; i--)
  {
    if (last->text[i] == '\\')
      count++;
  }
 
  // The pipe character is escaped with a backslash
  if ((count % 2) != 0)
    return false;
 
  return true;
}

void filter_text(struct Buffer *buf, char **env_list)
{
  // Trim the | (pipe) character
  size_t len = buf_len(buf);
  if (len == 0)
    return;
 
  if (buf->data[len - 1] == '|')
    buf->data[len - 1] = '\0';
 
  mutt_debug(LL_DEBUG3, "execute: %s\n", buf_string(buf));
  FILE *fp_filter = NULL;
  pid_t pid = filter_create(buf_string(buf), NULL, &fp_filter, NULL, env_list);
  if (pid < 0)
    return; // LCOV_EXCL_LINE
 
  buf_reset(buf);
  size_t n = fread(buf->data, 1, buf->dsize - 1, fp_filter);
  mutt_file_fclose(&fp_filter);
  buf_fix_dptr(buf);
 
  int rc = filter_wait(pid);
  if (rc != 0)
    mutt_debug(LL_DEBUG1, "filter cmd exited code %d\n", rc);
 
  if (n == 0)
  {
    mutt_debug(LL_DEBUG1, "error reading from filter: %s (errno=%d)\n",
               strerror(errno), errno);
    buf_reset(buf);
    return;
  }
 
  char *nl = (char *) buf_find_char(buf, '\n');
  if (nl)
    *nl = '\0';
  mutt_debug(LL_DEBUG3, "received: %s\n", buf_string(buf));
}

int expando_filter(const struct Expando *exp, const struct ExpandoRenderCallback *erc,
                   void *data, MuttFormatFlags flags, int max_cols,
                   char **env_list, struct Buffer *buf)
{
  if (!exp || !exp->node)
    return 0;
 
  struct ExpandoNode *node = exp->node;
 
  bool is_pipe = check_for_pipe(node);
  int old_cols = max_cols;
  if (is_pipe)
    max_cols = -1;
 
  int rc = expando_render(exp, erc, data, flags, max_cols, buf);
 
  if (!is_pipe)
    return rc;
 
  filter_text(buf, env_list);
 
  // Strictly truncate to size
  size_t width = 0;
  size_t bytes = mutt_wstr_trunc(buf_string(buf), buf_len(buf), old_cols, &width);
  buf->data[bytes] = '\0';
 
  return width;
}