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-rw-r--r--user/tlecarrour.mdwn37
-rw-r--r--user/tlecarrour/auto-apt.mdwn57
-rw-r--r--user/tlecarrour/memstat.mdwn162
-rw-r--r--user/tlecarrour/patch_life_cycle.mdwn88
-rw-r--r--user/tlecarrour/porting_guide_for_dummies.mdwn203
-rw-r--r--user/tlecarrour/rng-tools.mdwn56
-rw-r--r--user/tlecarrour/suckless-tools.mdwn79
-rw-r--r--user/tlecarrour/up-imapproxy.mdwn54
8 files changed, 736 insertions, 0 deletions
diff --git a/user/tlecarrour.mdwn b/user/tlecarrour.mdwn
new file mode 100644
index 00000000..12fc46b5
--- /dev/null
+++ b/user/tlecarrour.mdwn
@@ -0,0 +1,37 @@
+[[!meta copyright="Copyright © 2010 Free Software Foundation, Inc."]]
+
+[[!meta license="""[[!toggle id="license" text="GFDL 1.2+"]][[!toggleable
+id="license" text="Permission is granted to copy, distribute and/or modify this
+document under the terms of the GNU Free Documentation License, Version 1.2 or
+any later version published by the Free Software Foundation; with no Invariant
+Sections, no Front-Cover Texts, and no Back-Cover Texts. A copy of the license
+is included in the section entitled [[GNU Free Documentation
+License|/fdl]]."]]"""]]
+
+
+Tanguy LE CARROUR
+=================
+
+Homepage: *none*
+E-mail: [tanguy@bioneland.org](mailto:tanguy@bioneland.org)
+
+I am a Hurd enthusiast and new contributor, mostly working on porting packages
+for **Debian GNU/Hurd**.
+
+
+Contributions
+-------------
+
+
+### Porting Debian Packages:
+
+See the [[package porting general introduction|hurd/porting/guidelines]] and
+my [[porting guide for dummies|porting_guide_for_dummies]].
+
+For each patch make sure to respect the [[patch life cycle|patch_life_cycle]].
+
+* [[memstat]] (PATH_MAX), **draft**
+* [[auto-apt]] (PATH_MAX), **discussing**
+* [[rng-tools]] (PATH_MAX), **discussing**
+* [[suckless-tools]] (PATH_MAX), **draft**
+* [[up-imapproxy]] (PATH_MAX), **started**
diff --git a/user/tlecarrour/auto-apt.mdwn b/user/tlecarrour/auto-apt.mdwn
new file mode 100644
index 00000000..6a5adb80
--- /dev/null
+++ b/user/tlecarrour/auto-apt.mdwn
@@ -0,0 +1,57 @@
+[[!meta copyright="Copyright © 2010 Free Software Foundation, Inc."]]
+
+[[!meta license="""[[!toggle id="license" text="GFDL 1.2+"]][[!toggleable
+id="license" text="Permission is granted to copy, distribute and/or modify this
+document under the terms of the GNU Free Documentation License, Version 1.2 or
+any later version published by the Free Software Foundation; with no Invariant
+Sections, no Front-Cover Texts, and no Back-Cover Texts. A copy of the license
+is included in the section entitled [[GNU Free Documentation
+License|/fdl]]."]]"""]]
+
+
+auto-apt
+========
+
+When you want to build a program from source and it fails due to missing headers. Auto-apt can search what package would provide the header files.
+(from [[https://help.ubuntu.com/community/AutoApt]])
+
+
+[[!toc startlevel=2]]
+
+
+* * *
+
+
+Log
+---
+
+* **Started**: 2012-01-24
+* **Discussed**: [2012-01-26](http://lists.debian.org/debian-hurd/2012/01/msg00129.html)
+* **Draft Submitted**: -
+* **Submitted**: -
+* **Accepted**: -
+
+
+* * *
+
+
+ToDo
+----
+
+The output of `grep -R PATH_MAX auto-apt-0.3.22/*` is a bit long. It contains files that have been patched using `#define PATH_MAX XYZ`.
+Here is the only file of interest:
+
+ pkgcdb/pkgtab.c: char buf[PATH_MAX];
+ pkgcdb/pkgtab.c: assert(p - pkg < PATH_MAX);
+ pkgcdb/pkgtab.c: static char buf[PATH_MAX];
+ pkgcdb/pkgtab.c: assert(len < PATH_MAX);
+
+
+* * *
+
+
+Comments
+--------
+
+Work in progress, see related [thread](http://lists.debian.org/debian-hurd/2012/01/msg00129.html).
+
diff --git a/user/tlecarrour/memstat.mdwn b/user/tlecarrour/memstat.mdwn
new file mode 100644
index 00000000..d8c65884
--- /dev/null
+++ b/user/tlecarrour/memstat.mdwn
@@ -0,0 +1,162 @@
+[[!meta copyright="Copyright © 2010 Free Software Foundation, Inc."]]
+
+[[!meta license="""[[!toggle id="license" text="GFDL 1.2+"]][[!toggleable
+id="license" text="Permission is granted to copy, distribute and/or modify this
+document under the terms of the GNU Free Documentation License, Version 1.2 or
+any later version published by the Free Software Foundation; with no Invariant
+Sections, no Front-Cover Texts, and no Back-Cover Texts. A copy of the license
+is included in the section entitled [[GNU Free Documentation
+License|/fdl]]."]]"""]]
+
+
+memstat
+=======
+
+Lists all the processes, executables, and shared libraries that are using up virtual memory. It's helpful to see how the shared memory is used and which 'old' libs are loaded.
+**Home page**: [[http://sourceforge.net/projects/memstattool]]
+
+[[!toc startlevel=2]]
+
+
+* * *
+
+
+Log
+---
+
+* **Started**: 2012-01-20
+* **Discussed**: [2012-01-21](http://lists.debian.org/debian-hurd/2012/01/msg00081.html)
+* **Draft Submitted**: [2012-01-25](http://lists.debian.org/debian-hurd/2012/01/msg00122.html)
+* **Submitted**: -
+* **Accepted**: -
+
+
+* * *
+
+
+ToDo
+----
+
+Here is the output of `grep -R PATH_MAX memstat-0.9/*`:
+
+ memstat.c: char *p, major[8], minor[8], buff[PATH_MAX + 300], *path, perm[4];
+ memstat.c: char linkname[PATH_MAX], filename[PATH_MAX];
+ memstat.c: if ((len = readlink(filename, linkname, PATH_MAX)) == -1) {
+
+
+* * *
+
+
+Comments
+--------
+
+Here are comments on the patch...
+
+ +#define FMT_PROC_MAPS "/proc/%d/maps"
+ +#define FMT_PROC_EXE "/proc/%d/exe"
+
+Define string formats.
+
+ static void read_proc(void)
+ {
+ unsigned int nread, pid;
+ unsigned long inode, lo, hi, offs;
+ - char *p, major[8], minor[8], buff[PATH_MAX + 300], *path, perm[4];
+ + char *p, major[8], minor[8], *path, perm[4];
+ + char *buff = NULL;
+ + size_t buff_size = 0;
+
+In this function we turn `buff` into dynamically allocated string.
+
+
+ - sprintf(buff, "/proc/%d/maps", pid);
+ - f = fopen(buff, "r");
+ + char filename[sizeof(FMT_PROC_MAPS) + (sizeof(int) * 3) + 1];
+ + sprintf(filename, FMT_PROC_MAPS, pid);
+ + f = fopen(filename, "r");
+
+Compute the maximum size of `filename` using `sizeof(int) * 3` as explainend in the [[porting guide|porting_guide_for_dummies]].
+
+
+ - while (fgets(buff, sizeof(buff), f)) {
+ + while (!feof(f)) {
+ + buff = get_line(f);
+ + if (buff == NULL)
+ + break;
+
+Read a line from the file using [[get_line()|porting_guide_for_dummies]].
+
+
+ - if ((strlen(buff) == 10) && (strcmp(buff, " (deleted)") == 0))
+ + if ((strlen(buff) == 10) && (strcmp(buff, " (deleted)") == 0)) {
+ + free(buff);
+ continue;
+ + }
+ nread = sscanf(buff, "%lx %lx %4s %lx %s %s %lu %as", &lo, &hi, perm, &offs, major, minor, &inode, &path);
+ + free(buff);
+
+Free the `buff` when it's not used anymore.
+
+
+ + buff_size = 4; /* size of the format string without "%x" expressions */
+ + buff_size += strlen(major);
+ + buff_size += strlen(minor);
+ + buff_size += sizeof(int) * 3 + 1; /* inode */
+ + buff_size += 1; /* '\0' */
+ + buff = malloc(buff_size);
+ + if (buff == NULL) {
+ + perror("Cannot allocate memory!");
+ + exit(1);
+ + }
+
+Compute the size that the `buff` must have.
+
+
+ - char linkname[PATH_MAX], filename[PATH_MAX];
+ - ssize_t len;
+ + char *linkname = NULL;
+ + struct stat sb;
+ + ssize_t len = -1;
+
+In this function we turn linkname into dynamically allocated string.
+filename will be declared later.
+
+
+ - sprintf(filename, "/proc/%d/exe", pid);
+ - if ((len = readlink(filename, linkname, PATH_MAX)) == -1) {
+ + char filename[sizeof(FMT_PROC_EXE) + (sizeof(int) * 3) + 1];
+ + sprintf(filename, FMT_PROC_EXE, pid);
+
+Same as above with `FMT_PROC_MAPS`.
+
+
+ + if (lstat(filename, &sb) == -1) {
+ + perror("lstat");
+ + deleted = 1;
+ + }
+ + else {
+ + linkname = malloc(sb.st_size + 1);
+ + if (linkname == NULL) {
+ + fprintf(stderr, "insufficient memory\n");
+ + deleted = 1;
+ + }
+ + else {
+ + len = readlink(filename, linkname, sb.st_size + 1);
+ + }
+ + }
+ + if (len < 0 || len > sb.st_size) {
+ fprintf(stderr, "Cannot read link information for %s\n", filename);
+ deleted = 1;
+ }
+ - linkname[len] = '\0';
+ + else {
+ + linkname[sb.st_size] = '\0';
+ + }
+
+Use `readlink()` as explained in the porting guide.
+Require lstat to get the link size.
+
+
+ + free(linkname);
+Free dynamically allocated variable that is not used anymore.
+
diff --git a/user/tlecarrour/patch_life_cycle.mdwn b/user/tlecarrour/patch_life_cycle.mdwn
new file mode 100644
index 00000000..0d9c31f4
--- /dev/null
+++ b/user/tlecarrour/patch_life_cycle.mdwn
@@ -0,0 +1,88 @@
+[[!meta copyright="Copyright © 2010 Free Software Foundation, Inc."]]
+
+[[!meta license="""[[!toggle id="license" text="GFDL 1.2+"]][[!toggleable
+id="license" text="Permission is granted to copy, distribute and/or modify this
+document under the terms of the GNU Free Documentation License, Version 1.2 or
+any later version published by the Free Software Foundation; with no Invariant
+Sections, no Front-Cover Texts, and no Back-Cover Texts. A copy of the license
+is included in the section entitled [[GNU Free Documentation
+License|/fdl]]."]]"""]]
+
+
+Patch Life Cycle
+================
+
+[[!toc startlevel=2]]
+
+
+* * *
+
+
+Start
+-----
+
+Follow the steps listed on the [[package porting page|porting_guide_for_dummies]].
+
+
+Discuss
+-------
+
+Send the patch for review to [debian-hurd@lists.debian.org](mailto:debian-hurd@lists.debian.org).
+**Before** sending the patch, make sure that you've solved all the known problems listed in the [[package porting general introduction|hurd/porting/guidelines]]
+and the [[porting guide for dummies|porting_guide_for_dummies]].
+
+
+Submit Draft
+------------
+
+When the patch is good enough, you can write the draft of the official bug report.
+This draft should first be sent for review to [debian-hurd@lists.debian.org](mailto:debian-hurd@lists.debian.org) with the patch attached.
+
+Here is an example for memstat:
+
+ Source: memstat
+ Version: 0.9
+ Severity: important
+ Tags: patch
+ User: debian-hurd@lists.debian.org
+ Usertags: hurd
+ X-DebBugs-CC: debian-hurd@lists.debian.org
+
+ Hi,
+
+ This patch solves the build problems for GNU/Hurd due to PATH_MAX
+ issues. The solution is to make dynamic string allocations instead of
+ using fixed length buffers. The patch involves one file, and is
+ trivial.
+
+ FIXME:
+ Is it really useful to check if BUFSIZ is defined?
+
+ TODO:
+ Should the "whole package" be tested with valgrind on GNU/Linux?!
+ If yes, is there a standard procedure to do it?!
+
+ Thanks!
+ Special thanks to Jérémie and Richard for their comments!
+
+ (Not submitted yet, comments are welcome.)
+
+Once it's been approved, you can proceed to the submission.
+
+
+Submit
+------
+
+The bug report is the same as above, with all the **FIXME**, **TODO** and final comment removed.
+Attach the patch and send it to [submit@debian.org](mailto:submit@debian.org).
+Convention for the attachment name is: `fix_FTBFS4Hurd.patch`
+
+
+Accept
+------
+
+Once the patch has been accepted, update your patch page!
+**Congratulations!**
+
+
+
diff --git a/user/tlecarrour/porting_guide_for_dummies.mdwn b/user/tlecarrour/porting_guide_for_dummies.mdwn
new file mode 100644
index 00000000..749344fd
--- /dev/null
+++ b/user/tlecarrour/porting_guide_for_dummies.mdwn
@@ -0,0 +1,203 @@
+[[!meta copyright="Copyright © 2010 Free Software Foundation, Inc."]]
+
+[[!meta license="""[[!toggle id="license" text="GFDL 1.2+"]][[!toggleable
+id="license" text="Permission is granted to copy, distribute and/or modify this
+document under the terms of the GNU Free Documentation License, Version 1.2 or
+any later version published by the Free Software Foundation; with no Invariant
+Sections, no Front-Cover Texts, and no Back-Cover Texts. A copy of the license
+is included in the section entitled [[GNU Free Documentation
+License|/fdl]]."]]"""]]
+
+
+Porting Guide for Dummies
+=========================
+
+The problems addressed here were encountered while working
+on fixing **PATH_MAX** and **MAXPATHLEN**.
+
+[[!toc startlevel=2 levels=3]]
+
+
+* * *
+
+
+Test on Hurd
+------------
+
+
+### Installing the required files
+
+As `apt-get source` will download and extract many files, you may want to create a dedicated folder for the package and work from there.
+
+ mkdir PACKAGE
+ cd PACKAGE
+ sudo apt-get build-dep PACKAGE
+ apt-get source PACKAGE
+
+
+### Trying to build the package
+
+ cd PACKAGE_SOURCE
+ dpkg-buildpackage -us -uc -rfakeroot -tc
+
+
+### Test a quick fix
+
+In all the files that use **PATH_MAX**, include those lines at the beginning.
+
+ #ifndef PATH_MAX
+ #define PATH_MAX 4196
+ #endif
+
+Try to rebuild the package and see if it's solved the problem.
+If yes, you can start working on the package.
+
+
+* * *
+
+
+Basic things
+------------
+
+### Maintaining a original version
+
+ mkdir old
+ cp -r PACKAGE_SOURCE old/
+
+
+### Coding style
+
+Follow the conventions used in the source code!
+
+ if (condition) {
+ do_smthg();
+ }
+
+is not the same as:
+
+ if (condition)
+ {
+ do_smthg();
+ }
+
+and is not the same as:
+
+ if (condition)
+ do_smthg();
+
+Pay attention to spaces surrounding, or not, arithmetic signs and symbols:
+
+ a = do_smthg( b + c );
+ a = do_smthg(b+c);
+
+
+### Indentation
+
+By default use 8 spaces as the size for 1 tab.
+Then figure out if the code uses tab + 1/2 tab:
+
+ ....if (condition) {
+ ------->do_smthg();
+ ....}
+
+or tab only:
+
+ ------->if (condition) {
+ ------->------->do_smthg();
+ ------->}
+
+
+### Creating a patch
+
+ diff -Naur old/PACKAGE-VERSION PACKAGE-VERSION > fix_FTBFS4Hurd.patch
+
+
+* * *
+
+
+Known problems
+--------------
+
+### Dynamically allocated buffer returned by a function
+
+Use a static buffer
+
+### Buffer used to format an expression containing an INTEGER
+
+The length of an INTEGER in a string can be up to sizeof (int) * 3 + 1.
+
+> The usual trick for "%d" is to use the constant 'sizeof (int) * 3 + 1'.
+I included + 1 for the sign, but it's not really necessary
+if we exepect sizeof(int) >= 2, which we probably should.
+**Jérémie Koenig**
+
+ log(MAX_INT)
+ = log(2 ^ 32)
+ = 32 * log(2)
+ = 4 * 8 * log(2)
+ = sizeof(int) * 2.40823997
+ < sizeof(int) * 3
+
+
+### Proper use of realloc()
+
+use a new_buff to check if everything went fine Free buf if realloc failed (and prog doesn't exit)
+
+
+### Reading lines from file
+
+Function to read line (no size limit, ending with "\n") from a file.
+
+ +static char *get_line(FILE *f)
+ +{
+ + char *buff = NULL;
+ + char *new_buff = NULL;
+ + size_t buff_size = 0;
+ + size_t last = 0;
+ +
+ + while (!feof(f)) {
+ + buff_size = buff_size ? buff_size * 2 : BUFSIZ;
+ + new_buff = realloc(buff, buff_size);
+ + if (new_buff == NULL) {
+ + free(buff);
+ + return NULL;
+ + }
+ + buff = new_buff;
+ + if (fgets(buff + last, buff_size - last, f) == NULL) {
+ + free(buff);
+ + return NULL;
+ + }
+ + last = strlen(buff);
+ + if (buff[last - 1] == '\n')
+ + return buff;
+ + }
+ + return buff;
+ +}
+
+
+### Proper use of readlink()
+
+One has to rely on lstat() to get the size of the link that readlink() returns.
+
+Declare what you need:
+
+ char *linkname = NULL;
+ struct stat sb;
+ ssize_t len = -1;
+
+Call lstat() and check return value:
+
+ if (lstat(filename, &sb) == -1) {
+
+Create a buffer of the appropriate size and check the return value:
+
+ linkname = malloc(sb.st_size + 1);
+ if (linkname == NULL) {
+
+Call readlink(), check return value and set the null char in the linkname:
+
+ len = readlink(filename, linkname, sb.st_size + 1);
+ if (len < 0 || len > sb.st_size) {
+ ...
+ linkname[sb.st_size] = '\0';
+
diff --git a/user/tlecarrour/rng-tools.mdwn b/user/tlecarrour/rng-tools.mdwn
new file mode 100644
index 00000000..329852a0
--- /dev/null
+++ b/user/tlecarrour/rng-tools.mdwn
@@ -0,0 +1,56 @@
+[[!meta copyright="Copyright © 2010 Free Software Foundation, Inc."]]
+
+[[!meta license="""[[!toggle id="license" text="GFDL 1.2+"]][[!toggleable
+id="license" text="Permission is granted to copy, distribute and/or modify this
+document under the terms of the GNU Free Documentation License, Version 1.2 or
+any later version published by the Free Software Foundation; with no Invariant
+Sections, no Front-Cover Texts, and no Back-Cover Texts. A copy of the license
+is included in the section entitled [[GNU Free Documentation
+License|/fdl]]."]]"""]]
+
+
+rng-tools
+=========
+
+Daemon to use a Hardware TRNG. The rngd daemon acts as a bridge between a Hardware TRNG (true random number generator) such as the ones in some Intel/AMD/VIA chipsets, and the kernel's PRNG (pseudo-random number generator).
+(from [[http://packages.debian.org/lenny/rng-tools]])
+
+[[!toc startlevel=2]]
+
+
+* * *
+
+
+Log
+---
+
+* **Started**: 2012-01-28
+* **Discussed**: [2012-01-30](http://lists.debian.org/debian-hurd/2012/01/msg00177.html)
+* **Draft Submitted**: -
+* **Submitted**: -
+* **Accepted**: -
+
+
+* * *
+
+
+ToDo
+----
+
+Here is the output of `grep -R PATH_MAX rng-tools-2-unofficial-mt.14/*`:
+
+ viapadlock_engine.c:static char cpudev_path[PATH_MAX+1];
+ viapadlock_engine.c:char devpath[PATH_MAX+1];
+
+
+* * *
+
+
+Comments
+--------
+
+Work in progress, see related [thread](http://lists.debian.org/debian-hurd/2012/01/msg00177.html).
+
+Even if the **PATH_MAX** can be easily fixed, some problems remain.
+The code uses `linux/types.h`, that has to be replaced by `sys/types.h`, but also uses `linux/random.h` which has no equivalent I know of.
+At least one source file is named after the OS: `rngd_linux.c`.
diff --git a/user/tlecarrour/suckless-tools.mdwn b/user/tlecarrour/suckless-tools.mdwn
new file mode 100644
index 00000000..a646fac3
--- /dev/null
+++ b/user/tlecarrour/suckless-tools.mdwn
@@ -0,0 +1,79 @@
+[[!meta copyright="Copyright © 2010 Free Software Foundation, Inc."]]
+
+[[!meta license="""[[!toggle id="license" text="GFDL 1.2+"]][[!toggleable
+id="license" text="Permission is granted to copy, distribute and/or modify this
+document under the terms of the GNU Free Documentation License, Version 1.2 or
+any later version published by the Free Software Foundation; with no Invariant
+Sections, no Front-Cover Texts, and no Back-Cover Texts. A copy of the license
+is included in the section entitled [[GNU Free Documentation
+License|/fdl]]."]]"""]]
+
+
+suckless-tools
+==============
+
+Home of dwm, dmenu and other quality software with a focus on simplicity, clarity, and frugality.
+**Home page**: [[http://suckless.org]]
+
+[[!toc startlevel=2]]
+
+
+* * *
+
+
+Log
+---
+
+* **Started**: 2012-01-31
+* **Discussed**: [2012-01-31](http://lists.debian.org/debian-hurd/2012/01/msg00191.html)
+* **Draft Submitted**: [2012-02-01](http://lists.debian.org/debian-hurd/2012/02/msg00001.html)
+* **Submitted**: -
+* **Accepted**: -
+
+
+* * *
+
+
+ToDo
+----
+
+Here is the output of `grep -R PATH_MAX suckless-tools-38/*`:
+
+ dmenu/dmenu_path.c: char buf[PATH_MAX];
+
+
+* * *
+
+
+Comments
+--------
+
+Here are comments on the patch...
+
+ void
+ scan(void) {
+ - char buf[PATH_MAX];
+ + char *buf = NULL;
+ + char *new_buf = NULL;
+ + size_t buf_size = 0;
+
+In this function we turn `buf` into dynamically allocated string.
+
+
+ while((ent = readdir(dp))) {
+ + buf_size = strlen(dir)+strlen(ent->d_name)+2;
+ + if(!buf || strlen(buf) < buf_size) {
+ + new_buf = realloc(buf, buf_size);
+ + if(!new_buf)
+ + die("realloc failed");
+ + buf = new_buf;
+ + }
+
+For each directory entry we create or adapt the buffer size.
+
+
+ }
+ + free(buf);
+
+We free the buf when done.
+
diff --git a/user/tlecarrour/up-imapproxy.mdwn b/user/tlecarrour/up-imapproxy.mdwn
new file mode 100644
index 00000000..fceea7d3
--- /dev/null
+++ b/user/tlecarrour/up-imapproxy.mdwn
@@ -0,0 +1,54 @@
+[[!meta copyright="Copyright © 2010 Free Software Foundation, Inc."]]
+
+[[!meta license="""[[!toggle id="license" text="GFDL 1.2+"]][[!toggleable
+id="license" text="Permission is granted to copy, distribute and/or modify this
+document under the terms of the GNU Free Documentation License, Version 1.2 or
+any later version published by the Free Software Foundation; with no Invariant
+Sections, no Front-Cover Texts, and no Back-Cover Texts. A copy of the license
+is included in the section entitled [[GNU Free Documentation
+License|/fdl]]."]]"""]]
+
+
+up-imapproxy
+============
+
+SquirrelMail's IMAP Proxy is a caching IMAP proxy server intended for use with webmail clients that cannot maintain persistent connections to an IMAP server.
+**Home page**: [[http://www.imapproxy.org]]
+
+[[!toc startlevel=2]]
+
+
+* * *
+
+
+Log
+---
+
+* **Started**: 2012-01-31
+* **Discussed**: -
+* **Draft Submitted**: -
+* **Submitted**: -
+* **Accepted**: -
+
+
+* * *
+
+
+ToDo
+----
+
+Here is the output of `grep -R PATH_MAX up-imapproxy-1.2.7/*`:
+
+ src/main.c: char f_randfile[ PATH_MAX ];
+
+
+* * *
+
+
+Comments
+--------
+
+Work in progress...
+
+Only the function that fills the buffer knows how long it can be.
+This function is `RAND_file_name()` and is part of **OpenSSL**.