Hello! This is crupest !
Welcome to my home page! Nice to meet you here! 🥰
If you have something interesting to share with me, feel free to email me at crupest@crupest.life. You can also create an issue in any of my repos on GitHub to talk anything to me.
Recent Posts (all)
Use systemd-nspawn to Create a Development Sandbox
systemd-nspawn is a great tool for creating development sandboxes. Compared to other similar technologies, it’s lightweight, flexible, and easy to use. In this blog, I’ll present a simple guide to using it.
Advantages I’ve been using traditional VMs and Docker for creating development environments. While both work fine, regardless of the performance, they suffer from being overly isolated. Two big headaches for me are host network sharing in traditional VMs and the immutability of Docker container ports and mounts.
systemd-nspawn is much more flexible. Every feature can be configured granularly and dynamically. For example, filesystem sharing can be configured to work like bind mounts, and network isolation can be disabled entirely, which exactly solves the two headaches mentioned above. Additionally, being part of systemd, it has the same excellent design as other systemd components.
Debian has a similar powerful tool called schroot. It is the official tool for automatic package building. Unfortunately, it seems to be a tool specific to Debian.
Usage systemd-nspawn consists of two parts that work together to achieve its VM functionality:
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Libc/POSIX Function "Extensions"
Recently, I’ve been working on porting some libraries to GNU/Hurd. Many (old) libraries use *_MAX constants on POSIX system interfaces to calculate buffer sizes. However, the GNU/Hurd maintainers urge against the blind use of them and refuse to define them in system headers. When old APIs are gone, compatibility problems come. To make my life easier, I’ll put some reusable code snippets here to help fix *_MAX bugs.
1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42 43 44 45 46 47 48 49 50 51 52 53 54 55 56 57 58 59 60 61 62 63 64 65 66 67 68 69 70 71 72 73 74 75 76 77 #include <stdlib.h> #include <stdarg.h> #include <unistd.h> #include <stdio.h> #include <errno.h> static inline char *xreadlink(const char *restrict path) { char *buffer; size_t allocated = 128; ssize_t len; while (1) { buffer = (char*) malloc(allocated); if (!buffer) { return NULL; } len = readlink(path, buffer, allocated); if (len < (ssize_t) allocated) { return buffer; } free(buffer); if (len >= (ssize_t) allocated) { allocated *= 2; continue; } return NULL; } } static inline char *xgethostname(void) { long max_host_name; char *buffer; max_host_name = sysconf(_SC_HOST_NAME_MAX); buffer = malloc(max_host_name + 1); if (gethostname(buffer, max_host_name + 1)) { free(buffer); return NULL; } buffer[max_host_name] = '\0'; return buffer; } static inline char *xgetcwd(void) { char *buffer; size_t allocated = 128; while (1) { buffer = (char*) malloc(allocated); if (!buffer) { return NULL; } getcwd(buffer, allocated); if (buffer) return buffer; free(buffer); if (errno == ERANGE) { allocated *= 2; continue; } return NULL; } } static inline __attribute__((__format__(__printf__, 2, 3))) int xsprintf(char **buf_ptr, const char *restrict format, ...) { char *buffer; int ret; va_list args; va_start(args, format); ret = snprintf(NULL, 0, format, args); if (ret < 0) { goto out; } buffer = malloc(ret + 1); if (!buffer) { ret = -1; goto out; } ret = snprintf(NULL, 0, format, args); if (ret < 0) { free(buffer); goto out; } *buf_ptr = buffer; out: va_end(args); return ret; }
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Use PaddleOCR
I guess OCR is not something new for us. While there are a lot of open source artificial intelligence engines to achieve this, I need a easy-to-use one.
Recently I got a task to convert images into text. The image number is fairly big. So it’s just impossible to OCR them one by one manually. So I wrote a python script to handle this tedious task.
Basic Processing The original images contain a identical useless frame around the part that I need. So a crop is required because it will improve the performance (of course, the image is smaller) and there are unrelated texts in the frame.
Cropping is a easy problem. Just install Pillow package with pip:
1 pip install Pillow Then use Pillow to do the cropping:
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My Friends (more links are being collected ...)
Always Remember
Die Philosophen haben die Welt nur verschieden interpretiert, es kömmt aber darauf an, sie zu verändern.
Translated from German: The philosophers have only interpreted the world in various ways, the point is to change it.