I have a file uploader and in order to validate the file is actually of the type expected, I am inspecting the binary and checking the ASCII identifying characters (see the PDF example here).
The majority of files have an ASCII identifier, however some don't (like XLS files)
How would I best identify these ones?
I see all have a hex values but as it stands, I don't currently have the capability of converting the binary data to Hex.
Workaround...
I don't have a HEX converter, but I can convert both Binary and HEX to Base64 so that is what I am doing and comparing the Base64 output.
Related
I have some wave files (.wav) and I need to convert them in base64 encoded strings. Could you guide me how to do that in Python/C/C++ ?
#ForceBru's answer
import base64
enc=base64.b64encode(open("file.wav").read())
has one problem. I noticed for some WAV files that I encoded the string generated was shorter than expected.
Python docs for "open()" say
If mode is omitted, it defaults to 'r'.
The default is to use text mode, which may convert '\n' characters to a platform-specific representation on writing and back on reading. Thus, when opening a binary file, you should append 'b' to the mode value to open the file in binary mode, which will improve portability.
Hence, the code snippet doesn't read in binary. So, the below code should be used for better output.
import base64
enc = base64.b64encode(open("file.wav", "rb").read())
Python
The easiest way
from base64 import b64encode
f=open("file.wav")
enc=b64encode(f.read())
f.close()
Now enc contains the encoded value.
You can use a bit simplified version:
import base64
enc=base64.b64encode(open("file.wav").read())
C
See this file for an example of base64 encoding of a file.
C++
Here you can see the base64 conversion of strings. I think it wouldn't be too difficult to do the same for files.
I want to write a string as binary data to a file.
This is my code:
FILE *ptr;
ptr = fopen("test.dat","wb"); // w for write, b for binary
fprintf(ptr,"this is a test");
fclose(ptr);
After i run the program and open the file test.dat, i read "this is a test" but not the binary data i want. Anyone can help me?
You seem to be somewhat confused; all data in typical computers is binary. The fact that you opened the file for binary access means it will have e.g. end-of-line conversions done, it doesn't change the interpretation of the data you write.
You're just looking at binary data whose representation is a bunch of human-readable characters. Not sure what you expected to find, that is after all what you put into the file.
The letter 't' is represented by the binary sequence 01110100 (assuming an ASCII-compatible encoding), but many programs will show that as 't' instead.
Notepad decodes the binary data and shows ASCII equivalent code for it.
If you need to see the binary equivalent of the stored data then use hex viewer softwares and open your file in it.e.g. WinHex.
Is any reason why calculated by CSUM MD5 hash is different from the same hash calculated by fciv program on Windows?
If FCIV output is set to XML, the hexadecimal hash values are stored in base64 encoded format. When you view the XML database directly, the base64 encoded representation of the hash value does not visually match the hexadecimal value that the console displays. FCIV decodes the base64 encoded hashes when it displays the contents of the database to the screen. Therefore, it displays the correct hexadecimal value.
try: fciv.exe -list -md5 -xml hashdb.xml
I have an rtf file which contains special character as it is without decode to hexadecimal or unicode. I am using lib rtf in c language.
Below is the content from the rtf file. It has not mentioned encoded mode.
\b0\fi-380\li1800 · Going to home
While parsing i will get some junk value for the character. How to get proper character from the rtf file if it contains any character in specula mode only.
Regards,
Try this:
\b0\fi-380\li1800 \u183? Going to home
How to do it:
https://stackoverflow.com/a/20117501/1543816
I am interested in writing utf-8 encoded strings to a file.
I did this with low level functions open() and write().
In the first place I set the locale to a utf-8 aware character set with
setlocale("LC_ALL", "de_DE.utf8").
But the resulting file does not contain utf-8 characters, only iso8859 encoded umlauts. What am I doing wrong?
Addendum: I don't know if my strings are really utf-8 encoded in the first place. I just keep them in the source file in this form: char *msg = "Rote Grütze";
See screenshot for content of the textfile:
alt text http://img19.imageshack.us/img19/9791/picture1jh9.png
Changing the locale won't change the actual data written to the file using write(). You have to actually produce UTF-8 characters to write them to a file. For that purpose you can use libraries as ICU.
Edit after your edit of the question: UTF-8 characters are only different from ISO-8859 in the "special" symbols (ümlauts, áccénts, etc.). So, for all the text that doesn't have any of this symbols, both are equivalent. However, if you include in your program strings with those symbols, you have to make sure your text editor treats the data as UTF-8. Sometimes you just have to tell it to.
To sum up, the text you produce will be in UTF-8 if the strings within the source code are in UTF-8.
Another edit: Just to be sure, you can convert your source code to UTF-8 using iconv:
iconv -f latin1 -t utf8 file.c
This will convert all your latin-1 strings to utf8, and when you print them they will be definitely in UTF-8. If iconv encounters a strange character, or you see the output strings with strange characters, then your strings were in UTF-8 already.
Regards,
Yes, you can do it with glibc. They call it multibyte instead of UTF-8, because it can handle more than one encoding type. Check out this part of the manual.
Look for functions that start with the prefix mb, and also function with wc prefix, for converting from multibyte to wide char. You'll have to set the locale first with setlocale() to UTF-8 so it chooses this implementation of multibyte support.
If you are coming from an Unicode file I believe the function you looking for is wcstombs().
Can you open up the file in a hex editor and verify, with a simple input example, that the written bytes are not the values of Unicode characters that you passed to write(). Sometimes, there is no way for a text editor to determine character set and your text editor may have assumed an ISO8859-1 character set.
Once you have done this, could you edit your original post to add the pertinent information?