From afe0c36d832df68c19373b2a99abba4fc840f0e1 Mon Sep 17 00:00:00 2001
From: Martin Kutlak <mkutlak@redhat.com>
Date: Tue, 21 May 2019 10:42:53 +0200
Subject: [PATCH] lib: add get env variable from a file

Introduced a new argument called 'delim' because /proc/PID/environ is
delimited with 0 but FILENAME_ENVIRON is escaped version of that file
with '\0's replaced by '\n'.

While /proc/PID/environ entries are always delimted by '\0' (even the
last one), other files might not use this style and the function must
handle EOF without the entry delimiter.

Cherry-picked from https://github.com/abrt/libreport/commit/a71e4149c85212c72af0cc67c5b99a5029491ed2
---
 src/include/internal_libreport.h |  2 ++
 src/lib/get_cmdline.c            | 38 ++++++++++++++++++++++++++------
 2 files changed, 33 insertions(+), 7 deletions(-)

diff --git a/src/include/internal_libreport.h b/src/include/internal_libreport.h
index d7bab4e..fc0242c 100644
--- a/src/include/internal_libreport.h
+++ b/src/include/internal_libreport.h
@@ -638,6 +638,8 @@ struct strbuf *strbuf_prepend_strfv(struct strbuf *strbuf,
 char* get_cmdline(pid_t pid);
 #define get_environ libreport_get_environ
 char* get_environ(pid_t pid);
+#define get_env_variable_ext libreport_get_env_variable_ext
+int get_env_variable_ext(int fd, char delim, const char *name, char **value);
 #define get_env_variable libreport_get_env_variable
 int get_env_variable(pid_t pid, const char *name, char **value);
 
diff --git a/src/lib/get_cmdline.c b/src/lib/get_cmdline.c
index 0fc0cbf..9e83994 100644
--- a/src/lib/get_cmdline.c
+++ b/src/lib/get_cmdline.c
@@ -149,15 +149,20 @@ char* get_environ(pid_t pid)
     return get_escaped(path, '\n');
 }
 
-int get_env_variable(pid_t pid, const char *name, char **value)
+int get_env_variable_ext(int fd, char delim, const char *name, char **value)
 {
-    char path[sizeof("/proc/%lu/environ") + sizeof(long)*3];
-    snprintf(path, sizeof(path), "/proc/%lu/environ", (long)pid);
+    int workfd = dup(fd);
+    if (workfd < 0)
+    {
+        perror_msg("dup()");
+        return -errno;
+    }
 
-    FILE *fenv = fopen(path, "re");
+    FILE *fenv = fdopen(workfd, "re");
     if (fenv == NULL)
     {
-        pwarn_msg("Failed to open environ file");
+        close(workfd);
+        perror_msg("fdopen()");
         return -errno;
     }
 
@@ -177,17 +182,18 @@ int get_env_variable(pid_t pid, const char *name, char **value)
         i = 0;
 
         /* Read to the end of variable entry */
-        while ((c = fgetc(fenv)) != EOF && c !='\0')
+        while ((c = fgetc(fenv)) != EOF && c != delim)
             ++i;
 
         /* Go to the next entry if the read entry isn't the searched variable */
         if (skip)
             continue;
 
+        const int eof = c != EOF;
         *value = xmalloc(i+1);
 
         /* i+1 because we didn't count '\0'  */
-        if (fseek(fenv, -(i+1), SEEK_CUR) < 0)
+        if (fseek(fenv, -(i+eof), SEEK_CUR) < 0)
             error_msg_and_die("Failed to seek");
 
         if (fread(*value, 1, i, fenv) != i)
@@ -201,3 +207,21 @@ int get_env_variable(pid_t pid, const char *name, char **value)
     fclose(fenv);
     return 0;
 }
+
+int get_env_variable(pid_t pid, const char *name, char **value)
+{
+    char path[sizeof("/proc/%lu/environ") + sizeof(long)*3];
+    snprintf(path, sizeof(path), "/proc/%lu/environ", (long)pid);
+
+    const int envfd = open(path, O_RDONLY);
+    if (envfd < 0)
+    {
+        pwarn_msg("Failed to open environ file");
+        return -errno;
+    }
+
+    const int r = get_env_variable_ext(envfd, '\0', name, value);
+    close(envfd);
+
+    return r;
+}
-- 
2.21.0